Uninterruptible Power System 800 Installation guide
Contents
1. Uninterruptible Power Supply UPS Planning and Installation Guide h SOLIDSTATE CONTROLS INC Solidstate Controls Incorporated 875 Dearborn Drive Columbus Ohio 43085 Tel 614 846 7500 Fax 614 885 3990 Uninterruptible Power Supply UPS Planning and Installation Guide Solidstate Controls Inc is pleased to furnish this Planning and Installation Guide to inform you about the UPS equipment and assist you in its installation The planning for an installation of electrical equipment as critical to your company as an uninterruptible power system UPS deserves and in some localities requires the attention of a qualified engineer or qualified electrician SCI is pleased to assist you or your technical staff in any way and has prepared this manual as a technical aid However nothing herein should be construed as a substitute for proper engineering of a specific installation Table Of Contents Introduction How to Size a UPS Load 0 eeeeeeeeeeeeceeeeeeeeeeeeeeeeeeaeseeeeeeaeeaes Pg 4 Section Electrical ConsideratiOns 0 ce ccccccceeceeseeeeceeseeeeeeeeseeeeeeeeeaees Pg 7 Section Il Physical amp Environmental Considerations c ceeeeeeeee Pg 15 Section Ill Battery Selection sirinin niari iieiea diea Pg 19 Section IV Battery Room Physical amp Environmental Considerations cccccccceeeeeseeeeeeeeereeteeees Pg 21 Section V Start Up Supervision ccecceseseeeeeceeeeeeeeteeceeeeeee2. Equipment SCI has a comprehensive program to provide Nuclear Class 1E equipment All such equipment is custom manufactured to the specific requirements of that particular location For detailed information please contact SCI PROPERTY OF SOLIDSTATE CONTROLS INC 4 7 1998 Section Ill Battery Selection All SCI UPS Systems are designed to operate from virtually any commercially available battery bank which exhibits the proper voltage range and current capacity to power that particular UPS Choosing the proper battery for the application then becomes one of examining these various parameters and choosing the one most suitable for the particular application The following is an analysis of various battery types and methods for sizing these batteries utilizing the battery manufacturer s data These batteries fall into two general types Stationary and sealed Stationary batteries are those which require ventilation due to the fact that they are designed to release gases into the atmosphere including hydrogen when they are charging Consequently these batteries also require routine maintenance such as periodic watering specific gravity and voltage checks In general these batteries are longer lived than sealed batteries Sealed batteries are those which are essentially sealed and release only small amounts of gas under high internal pressure as a safety precaution This would probably be a result of severe overcharging Normally the hyd
3. and proper polarity of each cell 7 Turn on the inverter and perform system output voltage current and frequency checks Make any necessary adjustments to the equipment 8 Acquaint the customer s personnel with the equipment and system operation Explain routine maintenance of the equipment including batteries SCI Field Service Technicians also provide detailed personalized training of customer s service personnel if required either at the time of start up or at some other time convenient to the customer The customer should discuss these requirements with our Field Service Manager PROPERTY OF SOLIDSTATE CONTROLS INC 41 7 1998 Section Vi Service And Training SOLIDSTATE CONTROLS INC is dedicated to providing the most reliable Uninterruptible Power Systems available Even as exacting as we build our equipment we recognize that some service and repair may one day be required With this in mind SCI has provided for UPS maintenance by having available a strong field service team offering service training to those customers who elect it SCI field service personnel are available on short notice to respond to our customers requests for maintenance and repair SCI maintains a complete history file on each unit which includes test data previous service trips and repairs This up to date file can aid the field service personnel in providing even faster repair by isolating and identifying a particular problem As a benefit
4. for new installations Add to this any lighting alarms and security loads which are required 3 In existing installations check the capacity of the step down isolation transformer supplying the critical load or check the size of the distribution panel feeding those loads 4 It may be necessary to contact the electrical contractor who installed the loads for load data In these last three cases be sure to determine if there are any three phase loads Even though there is a three phase distribution panel or isolation transformer there need not necessarily by any three phase loads C Crest Factor Capability Included in SCI UPS equipment is circuitry to allow the inverter to be compatible with loads exhibiting a high crest factor Today s electronic computers and instrumentation equipment are powered with high frequency switching power supplies which draw non linear current from the AC source Both SCl s Ferroresonant and our power transistor PWM UPS systems have the designed capability to supply these non linear high crest factor loads Without this capability the UPS will either need to be over sized or will experience unnecessary and potentially load damaging nuisance transfers while these high crest factor loads are operating For further information about non linear loads and crest factor control please refer to our technical paper on the subject D Electrical Service for the UPS The Power source must be of sufficient capacit
5. location Floor loading requirements may also help determine the type of racks which can be used in a particular location Standard two tier racks are the most economical and most commonly used models in commercial and industrial applications They do not include any side or end rails to restrain the battery cells Your building code may require shock protecting racks for Zone 1 area applications or seismic racks for Zones 2 3 or 4 applications If these racks are required SCI can quote prices and supply dimensions These racks are generally not available in space saving three tier or three step designs Most sealed batteries in cabinets are suited for UPC Zone 4 applications Since stationary batteries do require some routine maintenance adequate space must be allowed around the battery bank to accommodate safe and efficient maintenance The cells need to be visible in order to check electrolyte levels and be accessible when specific gravity and cell voltage checks are required PROPERTY OF SOLIDSTATE CONTROLS INC 4 7 1998 2 Ventilation All stationary batteries produce hydrogen gas while they are being charged Gassing does not become a problem until approximately 70 of the charge has been returned to the cells The battery room must have adequate ventilation preferably to the outside to prevent the build up of hydrogen gas in the room The size of the room and the size of the battery bank will determine the amount of ventilation requi
6. matching cabinet if desired or can supply a standard transformer of another manufacturer in their own floor mounted enclosure Some customers may wish to have their own electrical contractor supply and install this along with other necessary equipment F Output Distribution Panels The customer s existing distribution panels which previously supplied the computer loads should be re evaluated before utilizing with the UPS The inverter portion of the UPS can deliver only a small amount of current above its nameplate ratting before the output voltage drops off drastically Consequently the current available to trip the distribution breakers is severely limited Ideally breakers and or fuses should be selected to clear the possible faults without overloading the inverter When overloads do occur the static switch will transfer all loads to the bypass utility source without interruption where the large capacity will clear the fault Since all transfers involve some risk to the load all unnecessary transfers should be avoided For further information regarding fault protection please refer to UPS Systems Distributor Network Protection by Laura Andrei R amp D Engineer G Consideration Regarding AC Distribution for Computer Rooms An Uninterruptible Power System UPS is the most complete form of power conditioning available A UPS can provide complete protection from all forms of line voltage transients surges and sages long durati
7. E CONTROLS INC 2 7 1998 Three phase loads can be difficult to size especially if there is a mixture of both single and three phase devices in the system Please call SCI for sizing assistance for those three phase applications For the truly dedicated Section III of the SCI UPS Installation and Planning Guide discusses three phase applications PROPERTY OF SOLIDSTATE CONTROLS INC 3 7 1998 Section I Electrical Considerations A UPS Sizing Load Study The first step in sizing the UPS is to perform a thorough Load Study When performing the Load Study it is important that all possible considerations be made for present needs and any planned future expansion All loads need to be analyzed with respect to various parameters as described below The following is a discussion and examples of which loads need to be considered for a computer room and how to use this information in sizing the UPS The same procedure can be used for load studies for any critical load 1 Computer Main Frame or CPU 2 Printers 3 Disk Drivers 4 Plotters 5 C R T Terminals 6 Any Other peripherals 7 Emergency room lights alarms security and all other loads which must be supported when the computer is in operation 8 Any other DC loads 9 Any projected expansion in the near future Consider the planned addition of any peripherals CRTs printers etc or new or additional computers It is more economical to purchase one large UPS th
8. No bolting to the floor is required although some units have provision for bolting should the customer wish to do so F Inverter and Rectifier Charger Room Requirements Room Temperature All SCI Ferroresonant UPS systems are designed to operate at full load in an ambient temperature of 0 40 C 32 104 F 0 95 relative humidity to altitudes of 5 500 feet over 5 500 feet consult the factory All SCI Powerbase PWM UPS systems to altitudes of 4 920 feet However as with all electronic equipment operating over a prolonged period of time at elevated temperatures may be detrimental to the extended life of the equipment In all probability we would expect the normal temperature range to be between 70 80 F Some installations may require that equipment be designed to operate at 50 C 122F for periods of time when normal cooling or ventilation has failed SCI can design equipment to meet this parameter where it is determined to be necessary High temperatures do have a negative effect on virtually all electronic components For maximum service life plan the equipment room so that normal operating temperatures are between 65 90 F Appendix A shows actual worst case heat dissipation for our standard equipment which will aid you in determining ventilation and air conditioning needs Since products do change frequently you may contact SCI to verify current heat dissipation data Cleanliness The equipment room should be relatively free
9. Sometimes the device label will state a wattage value and this is particularly true for small loads below 800 watts Many small UPS systems will have their capacity stated in watts rather than volt amperes The ratio of watts over VA i e W VA gives us a measure of power utilization called the power factor p f For example a computer with a volt ampere rating of 120 VA and a wattage rating of 96 watts has a power factor of 0 8 96 watts 0 8 p f 120 VA A good rule of thumb is to assume a power factor of 0 8 if both the wattage and volt ampere rating are not known For example an IBM desktop computer the PS 2 Model 30 has the following label attached in the back CPU B W Monitor 100 125 VAC 100 125 VAC 1 5A QA 50 60 Hz 60 Hz PROPERTY OF SOLIDSTATE CONTROLS INC 41 7 1998 Notice that the wattage is not known nor is the power factor Since in the U S 120 VAC is the nominal value of input voltage we can calculate the CPU s volt amperes VA directly IBM CPU 120 V x 1 5 A 180 VA If we use our rule of thumb and assume a power factor of 0 8 then 180 VA x 8 144 Watts W For those who love details The value difference between 180 VA and 144 W 36 VA circulates as unused power between the input power source and the computer So at this point we have two numbers 180 VA and 144 W which one do we use It depends on how the UPS capacity is stated The SCI Powerbase UPS have their capacities stated in Vol
10. aesaeseeteeeeaeeaee Pg 24 Section VI Service and Training cececeeeeseeeeceeeeeeeeeceeeeeeeeesaeeaeeeseaeeaeeaes Pg 25 Blank Page for Notes ccccecceceeseseeceeeeeeeeecaeseeseaesaeseseeteaeeaes Pg 27 PROPERTY OF SOLIDSTATE CONTROLS INC 7 98 How To Size Ups Loads Good data on power consumption is often hard to get for small loads such as personal computers Most equipment below for example 800 Watts will be 120 VAC single phase 60 Hz rated Sometimes with a dual rating for 50 Hz And 240 VAC for overseas usage Usually each component of the computer system will have a tag placed near the location the power cord enters the device Underwriter s Laboratory UL requires that at a minimum the voltage amperage and frequency be identified The arithmetic product of the voltage and the amperage i e V x A gives a result in Volt Amperes often stated simply VA The Volt Ampere VA is a universally accepted measure of electrical capacity for the UPS industry VA capacity simply states that a given device may draw so many amps A at a particular voltage V This is often a worst case value Many computer manufacturers overstate their equipment capacities by 20 or so to insure that the user provides adequate electrical service to the system The VA capacity tells us nothing about how efficiently the device utilizes the energy it receives The measure of actual electrical energy usage is the watt W
11. an two smaller ones to equal the same KVA rating Identify the voltage of each load whether it is single phase two phase or three phase and the frequency In an effort to minimize the size of the UPS and correspondingly the cost one should consider which devices if any need not be powered from the UPS For example if a computer room application requires only time to properly power down the system then you need not necessarily power your tape drives Also suppose there are ten 10 terminals connected Only one is necessary to power down In this way one can minimize the initial cost by purchasing a smaller size UPS which is likely to require less floor space less air conditioning and less annual operating costs If some loads have different input voltages it should be determined if they are convertible For example the main frame may be able to accept either 208Y 120 VAC three phase or 240 VAC three phase inputs If all other voltages are 120 V or 208Y 120 V then 208Y 120 V should be selected to power the main frame This will eliminate the need for and additional cost of special voltage transformers If any of the loads are three phase then a three phase U PS is required PROPERTY OF SOLIDSTATE CONTROLS INC 4 7 1998 A single phase UPS with a 120 V output can supply only a 120 V load However a three phase UPS with a 208Y 120 V output can supply either a 120 V single phase load a 208 V two phase load a 208 three pha
12. atures than are wet batteries If average daily temperatures in the battery room exceed 92 F you would be advised to consider using only wet stationary battery type When batteries are operated at temperatures below the standard of 77 F the available capacity and consequently the back up time is reduced It is significant to note that the percentage decrease in operating time will be greater than the percent loss of capacity and varies with the rate of discharge The effect is greater at high discharge rates such as fifteen minutes then at lower discharge rates such as eight hours Also since the charging voltage was based on 77 F reduced temperatures will result in increased recharge time a likelihood of cell imbalance and consequently a need for equalization B Physical Considerations 1 Floor Space Required Various styles and sizes of battery racks are available The selection of racks will probably be based on available floor space The two tier and two step racks will provide for easier servicing of the battery however the three tier and three step racks will save floor space For sealed batteries cabinets offer the most efficient use of floor space Battery banks are heavy and consequently floor loading may be a critical consideration Be sure the floor will be adequate Floor loading over 600 pounds square foot can be expected with some battery bank and rack combinations Obtain floor loading requirements for the proposed
13. ee phase inverter Other advantages such as lower inverter initial cost and simpler distribution no need to balance phases greatly outweigh the minimal inconvenience and slightly higher cost of the larger wire required for single phase PROPERTY OF SOLIDSTATE CONTROLS INC 2 7 1998 SOLIDSTATE CONTROLS INC
14. el ONLY QUALIFIED PERSONNEL SHOULD BE ALLOWED TO PERFORM MAINTENANCE ON THE EQUIPMENT I Security Security of the UPS room or location is as important as security of your computer room or other limited access area There is a potential for damage to the equipment as a result of ignorance carelessness or vandalism In addition an inexperienced operator could cause a loss of power to your Critical load by improperly manipulating the various controls on the UPS Consequently one may wish to limit access to the UPS area and monitor entry through your comprehensive alarm system J Storage of Supplies SCI recommends that the customer purchase and keep on hand replacement spare parts for the electrical equipment See Section VI of this manual These parts should be stored in a clean dry PROPERTY OF SOLIDSTATE CONTROLS INC 3 7 1998 location which is subject to the same temperature variations as allowed for the Inverter and Rectifier Charger i e 32 to 104 F K Vibration Standard UPS equipment is built to withstand mild intermittent building vibration However the equipment should not be considered to be seismic or earthquake proof It is impossible to predict a designed vibration tolerance for conditions that might be encountered in various installations If this is a concern it should be discussed with a SCI factory engineer SCI has vast experience in designing and qualifying seismic equipment L Nuclear Class 1E Qualified
15. electrical equipment Check the dimensional information on the appropriate data sheets for the floor space requirements The UPS equipment can be mounted with the back against a wall Side access is not specifically required however if side and rear access can be maintained it may be helpful should service become necessary A clear area in front of the unit of at least five 5 feet should be maintained for service personnel C Ventilation Clearance In order to provide for adequate ventilation the UPS should be installed in a room which has a least 12 inches of clearance over the unit The area above the UPS should be clear of any obstruction which would impede air flow Since cooling air enters through a grill at the bottom front of the equipment this area must also be kept clear of any obstructions D Floor Loading The Inverter and Rectifier Charger Some of the larger UPS systems are relatively heavy Care should be taken to assure that the floor loading requirements are not exceeded Reference can be made to the appropriate literature for dimensions and weights Floor loading can be expected to vary from 90 lbs Per square foot on smaller units to over 300 Ibs per square foot for our very large units One should plan accordingly PROPERTY OF SOLIDSTATE CONTROLS INC 7 98 E Equipment Mounting Requirements The Inverter and Rectifier Charger This equipment is designed to set on any floor which is adequate to handle the loading
16. gating on the thyristors at the proper time during each half cycle This change of conduction interval allows the PROPERTY OF SOLIDSTATE CONTROLS INC 7 7 1998 unit to maintain a constant output voltage with a varying input voltage A longer conduction period increases the DC output voltage and conversely a shorter period lowers the output voltage When the input voltage is high the thyristors are gated on later during each half cycle As a result in order to provide constant power we will necessarily see a high current spike at this point which we will refer to as form factor or crest factor Consequently even though the kilowatts KW which you pay for at the electrical meter are what you might expect based upon 92 94 efficiency this form factor or crest factor causes a higher than normal peak current demand which must be considered when selecting all upstream devices Note Although not true power factor this form factor or crest factor is many times expressed in those terms when discussing input requirements for rectifier chargers In general a good rule of thumb for estimating the input power requirements for a UPS system is to use 2 5 times the output kVA rating for our Ferroresonant units and 2 times the output rating for our PWM units All wiring transformers distribution breakers etc must be sized for the maximum currents as dictated by the NEC even though under normal operating conditions the input cur
17. hase loads for future expansion but only limited expansion room for three phase loads In the previous example we have been looking at continuous full load currents Any load which has a significant inrush current must also be identified In order to avoid an overload of the UPS it may be necessary to power up the various loads sequentially It may also mean that the way the loads are balanced on a three phase UPS may need to change so that all the high inrush loads are not on the same phase if possible In the earlier example if the 12 amp three phase continuous load had an inrush of five times its continuous rating 60 amp inrush and if all other loads on A phase were on and we attempted to start the load a total load of 141 5 amps would be seen on A phase This would cause an overload and all loads would be transferred to the bypass source until the overload was cleared If this is likely to happen often the consideration should be given to installing a large UPS Note that SCI inverters are designed to transfer to the bypass source upon an overload of 120 125 of full load As shown in the previous example if the 5 and 7 amp loads on B phase both had inrushes of ten times their rating and both could start at the same time then an overload would occur In this case consider moving on of the loads to C phase and perhaps an equal amount of load could be moved from C phase to B phase There are
18. ing purpose the requir8ed engine generator should be approximately 2 5 times the kVA rating of the UPS Please refer to SCI for specific data on specific equipment NOTE SCI can provide logic to cut back current limit while operating from the generator to help minimize the input requirements l Long Term Back Up DC Engine Generator An alternative to the use of an AC engine generator is the use of a DC engine generator In this application the generator size can be smaller due to the fact that the only over sizing required is that necessary to overcome the inverter losses Circuitry can be designed so the generator does not attempt to recharge the battery The generator size need only be from 1 3 to 1 5 times the kVA rating of the inverter J Grounding All SCI UPS enclosures are provided with grounding terminals located at the bottom Equipment should be grounded in accordance with the National Electrical Code and applicable local codes The electrical contractor will be aware of this necessity A good current reference is FIPS PUB 94 titled Guidelines on Electrical Power for ADP Installations dated September 21 1983 A copy of this can be obtained by writing to the National Bureau of Standards PROPERTY OF SOLIDSTATE CONTROLS INC 40 7 1998 Section Il Physical amp Environmental Considerations Site selection and planning The site selected for the UPS should be chosen with care since the type and amount of site preparation req
19. inverter were out of sync with the bypass Transfer is inhibited when out of sync to prevent an out of phase transfer from occurring The most common cause of an out of sync condition is if the facility in question is supported by an emergency stand by generator If the generator is powering motor loads in addition to the UPS the frequency will sag or overshoot anytime a load is applied or removed resulting in an inverter out of sync condition When three phase output inverters are used to power single phase distribution only one third of the inverter s total fault rating is available to clear a line to neutral fault If a single phase inverter is used it s entire fault rating is available to clear a line to neutral fault As an example if we considered a 15 KVA application using SCl s 500 of rated much higher than most fault current capability a three phase inverter would have a total of 208 amps available while a single phase inverter would be capable of 625 amps If the inverter were at full load these would be reduced to 166 amps and 500 amps respectively It would be highly unlikely that the three phase unit could clear a fast acting fuse much less a circuit breaker prior to current limiting Once the inverter goes into current limit the voltage will decrease and the entire load will be dropped In summary a single phase output inverter of any size rating will stand a much better chance of clearing a branch fault than a like sized thr
20. of dust and dirt and other airborne contaminates as heavy layers of dust will reduce the cooling efficiency of the electronic components Humidity and Condensation It is important that the room low temperature control be adjusted to maintain the room temperature above the dew point in order to prevent condensation of moisture on the electrical equipment G Unloading and Route Inspection Unloading Facilities Before the UPS equipment arrives at the installation site a number of checks need to be made of the facility Specific equipment size will determine the importance of each of the following items First check if the site has an adequate loading dock or an unloading area that is accessible to the trucker If unloading facilities are not adequate one might consider unloading at some other location which has proper facilities perhaps a nearby business that is willing to cooperate and using a smaller truck to deliver equipment to the site or using the services of a professional moving company PROPERTY OF SOLIDSTATE CONTROLS INC 2 7 1998 Moving Equipment At the unloading area a forklift may be neede3d to remove the equipment from the truck The forklift capacity should be checked to be sure it is adequate to handle the weight of the equipment This information is available from the data sheets Note that the date sheets give total weight If the outline drawing shows two equally sized cabinets the weight should be divided with ap
21. on V Start Up Supervision All UPS Systems which are not plug in compatible should be able to be installed by a qualified electrician Further SCI recommends that the customer purchase start up supervision to be sure that the equipment is installed and operating properly Severe damage could result if the equipment is installed improperly and start up initiated Also even though the equipment was tested and operating properly at the factory damage could have been sustained during shipment Our thoroughly trained Field Service Technicians utilize procedures to detect damage or other possible malfunctions due to shipping mishandling thus avoiding time consuming delays Start up supervision will include but not necessarily be limited to the following 1 Inspect incoming cable to assure that they are of adequate size Inspect the cable terminations in the unit to assure that they are properly made and are secure 2 Inspect the inter connections between bays to be sure that they have all been connected properly and securely 3 Perform voltage checks on all incoming services to assure all are within specification 4 Inspect the DC connections to assure that proper polarity has been observed 5 Inspect bypass source input and system output on three phase units to assure that proper phase rotation has been observed 6 Inspect battery installation checking for cell damage electrolyte level inter cell and inter tier or step connections
22. on brown outs and is the only device which can provide total no break back up protection against black outs It is commonly recognized that the various voltage related problems that trouble your computer come from two sources The first is atmospheric and accounts for approximately 20 of the total power problems The remaining 80 occurs within the users own building This is a result of a variety of conditions such as the presence of noise generating equipment like contactors relays switches and fluorescent lighting a general high power demand and the present of high inrush loads like motors and other large inductors Power problems also occur in the AC distribution system as a result of distribution breakers with dirty contacts which result in high impedance poor connections including ground connections incorrect grounding practices improperly sized ground neutral and power conductors and wiring errors Surprisingly wiring errors such as ground neutral reversals poor or loose connections and improper wire sizes occur frequently even in systems which have been in use for a long period of time and are unknowingly causing computer room problems The UPS can correct all voltage problems caused by the various previously mentioned conditions which exist up to the point of input to the UPS itself However if the AC distribution system which exists between the output of the UPS and the various computer loads and peripherals has any of the pre
23. proximately 60 in one cabinet and 40 in the other If the outline drawings show one larger and one smaller cabinet the weight should be divided with approximately 75 in the larger and 25 in the single smaller cabinet Route Inspection Determine how the equipment will be moved from the unloading area to the installation room and examine the passageway through the building to determine if there is adequate clearance to move the largest and heaviest package Remember add to the height the lift truck dolly or other device that will be used to move the equipment Especially check doorways or places where the equipment must go around a corner for proper clearance If an elevator is going to be used be sure the lift capacity and size is capable of handling the largest and heaviest package If a lift truck moving dollies etc are not available these should be rented or otherwise secured and be available when the equipment arrives H Fire and Safety Precautions In most cases building fire and safety codes establish the degree of protection required for installation of electrical equipment and batteries These should be followed for the installation of UPS systems Caution should be used to assure that the UPS is removed from areas in which flammable or explosive materials are kept or manufactured Personnel should be instructed in emergency shut down procedures Electrical equipment can pose certain hazards to equipment maintenance personn
24. red As a general rule ventilation should be adequate to provide from one to four air exchanges per hour Batteries do not gas when they are being discharged only when they are being charged Consequently loss of ventilation during a power outage is not a problem unless a critical operating temperature is reached in the room as a result C Electrical Consideration The end voltage is the minimum voltage that the cell will be allowed to reach during discharge In general with lead acid batteries it is recommended that the per cell end voltage not be allowed to go below 1 75 volts per cell for long term discharge batteries those over 60 minutes and 1 67 volts per cell for short term discharge batteries those 60 minutes and below The UPS DC voltage windows will also need to be compatible and should first be consulted This is necessary to prevent possible damage to the batteries To accomplish this the UPS should be equipped with a low DC disconnect feature to disconnect the UPS from battery when this level is reached This is a standard factor on all UPS systems but if not this feature should be requested D Battery Safety Precautions Batteries can provide many years of safe reliable service However the use and handling of batteries does pose some hazard unless safety precautions are exercised Before removing batteries from the pallet the customer must read and become familiar with the personal safety precautions regarding batte
25. rent can be expected to be much lower The following formula can be used to derive the rectifier charger input power requirements expressed in VA volt amperes CIP gt Vex Arx C1 PF x EF Ve z Charger equalize voltage Ar z Charger rated output in amperes C1 Charge current limit point typically 1 2 to 1 25 PF Charger input power factor typically 0 8 EF Charger efficiency typically 92 94 CIP Charger input power in VA volt amperes The following formula can then be used to derive the rectifier charger maximum input current This information is necessary in determining the UPS system input electrical service requirements Ac CIP V1x3 V1 3 phase AC input voltage at low line typically nominal voltage 10 or 15 3 1 732 Ac charger input current in amperes Note SCI can provide adjustable current limiting from 100 to 125 to aid in limiting the input current requirements under conditions where maximum current limiting is not desirable Bypass Source Supply The bypass source input must be supplied with an input voltage and frequency which exactly matches the output of the UPS For example if the UPS system output is 208Y 120 Vac 60 Hertz then the bypass source input must be 208Y 120 Vac 60 Hertz If this matching voltage is not available an appropriate transformer must be installed to provide the proper voltage SCI can PROPERTY OF SOLIDSTATE CONTROLS INC 8 7 1998 supply this transformer mounted in a
26. rogen and oxygen gases generated as a result of battery charging recombine within the battery as water No watering is necessary or possible The following batteries are examples of types normally used for UPS back up 1 Lead Calcium Stationary Batteries This type offers the best cost versus service reliability for stationary batteries available for UPS installations These batteries typically carry a 20 year warranty and have a 20 25 year life expectancy when used under float conditions Hydrogen generation is low compared to lead antimony batteries and when maintained at a float voltage of 2 25 volts cell do not require routine equalization Maintenance consists of watering terminal cleaning and checking electrolyte specific gravity at six month intervals Equalization is necessary only upon initial energization 2 Lead Antimony Stationary Batteries These batteries generally are equal in size and capacity to the lead calcium batteries Usually they are warranted for 15 20 years with a life expectancy of 15 22 years These batteries are normally better suited for applications where they are cycled rather than in full float application Hydrogen generation is considerably greater than lead calcium batteries and maintenance is required more frequently including periodic monthly equalization and weekly watering checks with additions as necessary 3 Nickel Cadmium Stationary Batteries NICAD batteries are the most expensive of the
27. ry handling In addition since batteries can be damaged due to incorrect handling the customer should also read all the general equipment precautions and handling instructions Briefly be aware that batteries can contain residual gas in the cells even during shipping Do not smoke or otherwise introduce flames sparks or other potential sources of ignition into the battery area Batteries are usually shipped wet filled with sulfuric acid electrolyte for lead acid types or potassium hydroxide for nickel cadmium types Both are caustic Be careful to keep them upright at all times Batteries can supply very high short circuit currents Remove all rings and jewelry Use only insulated tools Keep all metal tools or metal parts which could be dropped across the battery terminals away from the batteries Before stationary batteries are installed the battery room should be equipped with an emergency eye wash and the customer should become familiar with its operation He should also have available full eye protection rubber gloves and apron to protect eyes and skin from contact with the sulfuric acid electrolyte These items can be ordered with the battery or the customer can order from his preferred source and have available before the batteries arrive For further information regarding batteries refer to Selection and Sizing of Batteries for UPS Back up by Kenneth E Eppich Sales Engineer PROPERTY OF SOLIDSTATE CONTROLS INC 2 7 1998 Secti
28. se load or a 208Y 120 V three phase load In determining the size of a three phase UPS single phases loads can be distributed between each of the three phases However one large single phase load can be connected to only one phase of a three phase UPS This one load may well determine the size of the system even though the other loads may be very small Example STEP 1 Identified Loads 1 phase 120 V loads 2 phase 208 V loads 3 phase 208 V loads 75 0 amp 1 5 amp 12 0 amp 5 amp 5 0 amp 3 5 amp 1 5 amp 7 0 amp 2 5 amp 5 0 amp 3 0 amp STEP 2 Balancing Loads Three Phase UPS Output A phase B phase C phase 75 0 5 0 2 5 1 phase loads 7 0 3 0 1 phase loads 3 5 1 phase loads 0 5 1 phase loads 1 5 1 5 2 phase loads 12 0 12 0 12 0 3 phase loads 1 5 1 5 1 5 3 phase loads 5 0 5 0 5 0 3 phase loads 93 5 32 5 29 5 STEP 3 Select UPS Size The actual minimum kVA required is calculated by multiplying the highest phase current times the line to neutral voltage times three divided by 1000 kVA Amps highest x Voltage line to neutral x 3 1000 kVA 93 5 x 120 x 3 33 66 kVA 100 PROPERTY OF SOLIDSTATE CONTROLS INC 5 7 1998 Selecting from our standard sizes we find that we must supply a three phase 40 kVA UPS which has a 111 amp AC output per phase One can see that A phase is 84 loaded while B and C phases are only 27 loaded which means that there is substantial room for additional single p
29. stationary types discussed costing approximately two to three times calcium batteries Although it requires 92 cells of nickel cadmium to equal 60 cells of lead calcium they still have an advantage in being smaller in size and weight for a given capacity They also have excellent low temperature and high temperature properties and have an exceptionally long service life even at high temperatures Service life expectancy under normal conditions is approximately 25 years or more PROPERTY OF SOLIDSTATE CONTROLS INC 4 7 1998 4 Sealed Maintenance Free Batteries As previously discussed sealed batteries are those which due to special construction do not normally vent gas into the atmosphere and because they are sealed require no routine water additions Because they do not gas they are well suited for installation into an office area or computer room environment where special ventilation would be difficult or impractical to provide These two advantages present cost savings which should be considered when evaluating your battery requirements Sealed batteries lend themselves well to cabinet mountings and as a result can be attractively packaged for installation in an office or computer room along with the UPS system One can also recognize sealed batteries by the use of names such as Gel Cell Absorbed Electrolyte Starved Electrolyte or Suspended Electrolyte A word of caution Sealed batteries are maintenance free only in the sense they req
30. t amperes but the DataShield UPS have their capacities stated in watts Use whichever number is appropriate to the UPS system selected So far weve only covered the CPU but the calculations for the monitor are similar IBM Monitor 120 V x 9 A 108 VA108 VA x 8 86 W Recap CPU VA Watts IBM model 30 CPU 180 VA 144 W IBM BW Monitor 108 VA 86 W System Total 288 VA 230 W Thus we should be looking at a UPS with a V rating of 300 VA or a wattage rating of approximately 240 W Notice we re being conservative in that the derating factor of 20 was not used It is good design practice to oversize the UPS to take care of those equipment additions such as tape drives and modems that invariably get added to the computer system later In larger computer systems such as those supplied by IBM DEC and Data General detailed computer printouts listing the volt ampere wattage and peak current of each device can be obtained from the computer manufacturer s local sales office These print outs are essential for accurate comprehensive sizing of the UPS system We have not mentioned three phase power which is found in larger computer systems but the principles are much the same i e the individual device volt ampere VA ratings can be directly added to produce a composite value In these larger 3 phase systems typically above 10 000 VA or commonly written 10 KVA wattage is almost never used as sizing measure PROPERTY OF SOLIDSTAT
31. to those customers who choose to perform their own repair SCI has a full time service expert who by telephone can direct the customer s service technician through a step by step program of trouble shooting and repair in order to get the customer s equipment back on line in the shortest possible time PROPERTY OF SOLIDSTATE CONTROLS INC 41 7 1998 SINGLE or THREE PHASE Although it is common for UPS larger than 10 KVA to be specified with three phase output industrial distributed control systems rarely consist of any component that actually requires true three phase power Particularly on smaller systems under 50 KVA there are some very real technical advantages to single phase distribution Unlike a typical building distribution system which has relatively low source impedance an inverter is a high impedance power source This high impedance effectively limits the amount of fault current available to clear downstream branch faults Although under normal operating conditions most UPS clear downstream faults and short circuits by transferring the load to the low impedance bypass line via the static switch there are operating conditions that will need the inverter to be capable of clearing a faulted branch circuit The most obvious of these situations would be if the bypass line were not present due to a power failure in which case the inverter would be operating off the battery A not so obvious and rarely considered case would be if the
32. uire no electrolyte checks or water addition It is important that the battery terminal connections be inspected and re torqued periodically to maintain a sound connection Life expectancy and manufacturer s warranties vary from 1 year to 20 years with a corresponding variation in price As an average a 10 year sealed battery on an open rack will be priced approximately equal to the lead calcium 20 year wet battery PROPERTY OF SOLIDSTATE CONTROLS INC 2 7 1998 Section IV Battery Room Physical And Environmental Consideration A Battery Room Temperature Since battery operation results from a chemical reaction temperature plays a significant role in performance and life A standard temperature of 77 F 25 C is used to rate the batteries It is recommended that the battery room temperature be maintained as close as possible to this temperature 72 80 F would be acceptable Care should be taken not to locate batteries where they will be in direct sunlight or near a register which might subject one or more cells to high or low temperatures The temperature differential between all cells in a battery bank should no be more than 5 F Although battery capacity improves considerably at higher discharge rates as the temperature increases there is also a significant decrease in battery life An increase in periodic maintenance especially watering can also be expected with stationary types Sealed batteries are less tolerant of high temper
33. uired will vary according to the specific location and its relative location to the load A Locating the UPS The relative location of the UPS to the load is important for several reasons First the greater the distance between the UPS and the load the longer will be the interconnection cables the longer the cables the larger the wire will need to be in order to minimize the voltage drop in the wires This means greater expense For example a 20 kVA UPS with 120 VAC single phase output of 167 amps if used with 2 0 gauge wire ahs a voltage drop of 2 7 volts in 200 feet The a 500 MCM cable the voltage drop is only 0 7 volts However 500MCM wire is almost four times the size of the 2 0 gauge and proportionally more expensive Second and most important is the fact that these longer cables are more likely to pick up electrical noise from outside sources than are shorter cables simply because they are more likely to pass near noise generating equipment or other noise carrying conductors The elimination of electrical noise is one benefit of the UPS It is important to keep these cable lengths as short as possible and removed from the proximity of other cables or noise generating equipment such as motors switches etc If long cable runs are unavoidable greater care should be exercised in cable routing and sizing B Floor Space Requirements The Inverter and Rectifier Charger It is important that adequate floor space be provided for the UPS
34. usually many load considerations which must be looked at in sizing the UPS Be sure that all possibilities which might jeopardize the integrity of the continuous power have been considered B UPS Sizing Estimating from Available Data It may be necessary for quotation purposes to estimate the size of a UPS required for a particular installation where time does not permit a detailed Load Study 1 With all equipment operating one method would be to use a clamp on ammeter For a single phase two wire system measure the hot leg The kVA rating is calculated by multiplying the measured current times the line voltage divided by one thousand kVA amps x voltage 1000 For a single phase three wire system 240 120 measure each hot leg The kVA rating is the highest current reading multiplied times the line to neutral voltage multiplied times two divided by one thousand kVA amps highest x voltage line to neutral x 2 1000 For three phase systems measure all three hot legs The kVA rating is calculated by multiplying the highest current reading times the line to neutral voltage times three divided by one thousand kVA amps highest x voltage line to neutral x 3 1000 PROPERTY OF SOLIDSTATE CONTROLS INC 6 7 1998 If it is not possible to measure the actual current it may be necessary to use one of the following 2 Obtain load profile from manufacturer for the individual loads This will probably be necessary
35. viously mentioned problems voltage fluctuations may be re introduced onto the clean power generated by the UPS and as a result trouble with the computer system may continue It is therefore to the user s benefit to be sure that this AC distribution system is designed and operating properly One would be cautioned not to assume that your AC distribution is error free but that it be properly analyzed by experts in that field Many such AC distribution systems have been designed by experts and have AC verifications performed periodically at least one a year to assure that everything is operating properly that vibration has not loosened any connections that circuit breakers have clean low impedance contacts that no loads have been added improperly and that breaker and wire current ratings have PROPERTY OF SOLIDSTATE CONTROLS INC 9 7 1998 not been exceeded If this is not being done one would be advised to contact experts in that field to aid you in performing this important periodic analysis One should also be aware that some computer peripherals such as printers are themselves noise generators and that proper filters should be used on these lines to prevent the transmission of this noise from one device to another H Long Term Power Back Up AC Engine Generator There are several options open to the customer to supply his critical load in the event of a long term power outage One is to provide a battery bank large enough to carr
36. y the load for the prescribed length of time see discussion of Battery Sizing Selection Installation The other is to utilize an engine generator which can supply the load almost indefinitely If the customer has an existing engine generator he may wish to utilize it for back up purposes There are however a number of points which should be understood before using an engine generator Even though an engine generator can be used for long term back up batteries will still be needed In the event of a power outage the engine generator will need to be started If it has not been started for some time there may be some difficulty getting it started Once started it will need to be brought up to speed before a steady voltage and frequency is established During this period of time batteries will be needed as back up to the UPS The engine generator probably cannot supply the computer directly Although the engine generator is adequate for loads not requiring precise power such as lighting this is obviously not adequate for the computer The nature of the engine generator is such that we can expect both voltage and frequency to be constantly varying The proper method of utilizing the engine generator for long term back up is to supply power to the Rectifier Charger thereby utilizing the UPS for voltage and frequency regulations The engine generator manufacturer should also be made aware that the load will be of an SCR type For estimat
37. y to handle the worst case demands for the UPS Primary power installations for the UPS is the responsibility of the customer Future expansion should be considered in determining power requirements The customer is also responsible for the installation of any input distribution panels external battery disconnect switch as required by the NEC and or local codes output distribution panels and wiring to the loads unless such has been bid by SCI as part of the customer package Input Power Considerations and Distribution Consideration must be given to the input distribution panels for the UPS What presently exists for the load may not be too small due to the losses in the UPS itself the additional battery recharge capability and the overload capacity of the rectifier charger Some installations may have chosen a larger rectifier charger than that which would normally be supplied due to some additional DC loads or the customer s desire to recharge the batteries at a faster rate The maximum current ratings provided should be consulted for this determination It might appear on the surface that this device is very inefficient due to the rectifier charger high input current This is not the case Our rectifier chargers are approximately 92 94 efficient The reason for the high input current is this The output voltage regulation of the rectifier charger is accomplished by controlling the conduction interval of the thyristors This is done by
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