Loop Info-P-3-10.indd
Contents
1. which may be achieved with a loop measuring 6 on the short leg e Loops can be saw cut into concrete or asphalt They can be placed under brick pavers and asphalt or be imbedded in a poured concrete road surface Loop Info P 3 10 Loops that are physically adjacent to each other and operating on separate loop detectors may interfere cross talk with each other if they are operating on the same frequencies Changing the operating frequency on one of the loop detectors can eliminate this interference See page 7 for more information When connecting two loops to a single loop detector terminal always connect the loops in series If the loops are close together the direction of the windings should be considered Loops physically near each other and wound in the same direction electrically i e both Clockwise or Counter Clockwise will cause field cancellation effects a dead zone between the loops This may be desirable when two loops reverse loops are placed on each side of a sliding gate Wiring the loops in this manner will allow the gate to slide between the two loops without causing the loops to detect the gate If the loops are wound in electrically opposite directions i e one Clockwise and one Counter Clockwise field enhancement will occur between the loops effectively extending the field of sensitivity for the loop system See pages 5 and 6 for more information Determine the Number of Wire Turns Required for Each Loop Loop area2. Loop Info P 3 10 ep e The same careful attention to proper installation guidelines described for saw cut loops also apply to the installation of DoorKing 4 ft x 8 ft preformed loops e Preformed loops should be imbedded 2 to 3 inches below the surface of the poured concrete pavement Poured Concrete J Loop Lead in Preformed Loop Peee accepts 1 2 PVC conduit Styrofoam Blocks 1 RS 7 S T Reinforcement wires rebar and electrical wires
3. likes repel the fields of sensitivity are pushed up and away from each other creating a Dead Zone e The detection field shown is a relative profile of the detection height and will vary with the size of the loops spacing between the loops and the type of vehicle The relative height over the two inside wires increases as the loops are moved closer together and decreases as the loops are moved apart Inside Wire Field Outside Wire Field Counter clockwiseLoop 7 tS CCounter clockwise Loop Dead Zone Both loops wound counter clockwise 2 loops wound in the same direction repel the inside wire fields Winding the loops in the opposite direction Clockwise or Counter Clockwise electrically creates the effect of the electrical current passing through the closest edges of the loops in the same direction Since the electrical currents are flowing in the same direction the inductive fields of sensitivity created have opposite magnetic poles North or South toward each other Since unlikes attract the fields of sensitivity pull towards each other creating a larger zone of detection Winding the loops in electrically opposite directions could create an enhanced zone that would inhibit a slide gate from closing e The detection field shown is a relative profile of the detection height and will vary with the size of the loops spacing between the loops and the type of vehicle The relative height o
4. Sq Ft Multiply loop width by loop length Loop Area in Square Feet Number of Turns Required Note The number of turns should be increased by 1 turn if lead in wire or cable length is 500 ft or greater e During the construction of new installations i e concrete or asphalt a pre formed loop may be used as an alternate to the saw cut type Pre formed loops are typically encased in PVC or other durable materials to provide high reliability and long life Sizes may vary depending on the source of the pre formed loop DoorKing offers a variety of pre formed loops that come with 25 feet of lead in wire See page 10 for more information e The loop will tune to its environment Stationary or static metal objects such as conduits pipes metal grates etc will not affect the loop field High voltage electrical power lines either underground or overhead can affect the loop field In addition fluctuating electrical fields such as heating coils can cause loop lock ups and false detection e A heavy grid of reinforcing bars re bar may affect the loop field To minimize this DO NOT place a loop directly on the rebar Support the loop 1 2 inches above the rebar If possible make cuts or bends in the rebar grid directly below the loop Bars and electrical wires running at angles to the loop have less effect on the loop than those running parallel to the loop wires See page 10 for more information e f a single loop is used with a long
5. a metallic object enters this electrical field the loop detector senses a change in the field and generates an output usually activating a relay in a gate operator or other access control device that controls the operation of the gate There are three basic components in a loop detection system e Underground loop e Loop lead in wire or cable e Loop detector Loop Detector The loop detector is the electronic component that controls the loop system DoorKing offers loop detectors Models 9409 9410 that plug directly into the gate operator control board eliminating the wire harness and wiring connections other than the loop lead in wires These detector boards have a Underground Loop The loop is made from a continuous piece of wire NO SPLICES that is coiled around for a number of turns in a Square or rectangular pattern QQ SD Loop Lead in Wire or Cable The lead in wire or cable extends the two ends of the loop wire back to the loop The wire is embedded into pavement either as a preformed loop placed prior to paving or into a saw cut that is cut into existing pavement Both ends of this wire are then extended to the edge of the pavement detector On short runs Loop is within ten feet from the loop detector the two wires exiting the loop can be twisted together run in conduit to the operator and connected directly to the loop detector The lead in wire DoorKing recommends terminal strip where the
6. be far enough away from the shadow loop and or exit loop to avoid any cross talk Loop should to be far enough away from the reverse loops to or on a different loop detector frequency if detection fields overlap Page 7 avoid any cross talk or on a different loop detector frequency if detection fields overlap Page 7 Loop Lead In Wire A Loop Lead In Cable Closed Gate Position Open Gate Position Reverse Loop Automatic Exit Loop Reverse Loop Underground Loop Wire Automatic Exit Loop Install a separate loop detector Secondary Operator i Minimum loop size is 18 in x 48 in Pages 3 and 4 Loop Lead ins DoorKing preformed loops are 4 ft a tt Page ith Wire loop lead in should be twisted 6 turns per foot Pages 2 and 6 Normally located 20 100 feet away from the gate so that the gate is Use wire loop lead ins up to 10 ft away from operator Page 3 open or opening as you drive up to it Typically a loop lead in cable Use cable loop lead in farther than 10 ft away from operator if required Pages 2 and 6 will need to be installed Pages 2 and 6 All wire connections must be soldered between underground loop wire and loop lead ins Page 6 Loop should to be far enough away from the reverse loop and or Series wired loop lead ins should each be run to the operator before shadow loop to avoid any cross talk or on a different loop detector connecting them
7. e running at angles to the loop have less effect on the oop than those running parallel to the loop wires ic e f installed with asphalt pavement cover the loop with 1 inch minimum of soil or sand to protect the loop from hot asphalt Sand and Gravel Base 1 Minimum Depth Loop Lead In Wires Preformed Loop T connector accepts 1 2 PVC conduit Hold Down Stakes Loop Info P 3 10 Every slide loop installation is unique and may have specific problems that are not fully explained in this manual DoorKing highly recommends that the loop system is installed by a professional installer who understands loop systems and can foresee any problems that might occur for your specific installation Slide gates require the use of two reversing loops wired in series to a single loop detector for maximum vehicular protection Be sure that the two reverse loops are properly phased so that the gate can slide through the dead zone The optional automatic exit loop requires a second loop detector Loop Lead Ins Wire loop lead in should be twisted 6 turns per foot Pages 3 and 6 Use wire loop lead ins up to 10 ft away from operator Page 2 Use cable loop lead in farther than 10 ft away from operator if required Pages 2 and 6 All wire connections must be soldered between underground loop wire and loop lead ins Page 6 Series wired loop lead ins should each be run to the operator before connecting them together
8. l a l 121 I I l I I x I I I I I I I I I I I I Loop Detection Field or 4 ft Min gnon ra from Gate eng Shadow Loop See page 12 for more information 1 2 to 2 3rd Short Leg Length Detection Field Eg Frequency _ K DIP switches detector A common problem with loops are when they are positioned too close to each other and their detection fields overlap If the loops are on similar frequencies this can cause cross talk between the loops and false calls can occur in the loop detector Changing the frequency of one loop switching it s frequency as far away from the other loop s frequency as possible will eliminate the false calls Switching the frequency of a loop WILL NOT affect the loop s detection height Loop Info P 3 10 SECTION 2 LOOP INSTALLATION GUIDELINES In order to have a loop detection system operate as a reliable high performance system it is necessary to pay careful attention to the loop installation The use of proper installation techniques and the proper type of wire can reduce frustration aggravation and unnecessary service Calls After determining the size placement and number of turns of the loop See below text and illustrations on the next page Depth of Saw Cut The depth of the saw cut will vary depending on the number of wire turns typically 1 1 2 for 1 3 turns and 2 for 4 6 turns The backer rod should be at least 1 inch bel
9. lead in cable 500 feet or greater it is advisable to add an additional turn in the loop This increases the ratio of the loop inductance to the total inductance thereby improving loop sensitivity and overall loop system stability e The inductance of the loop in micro henries must fall within the tuning range of the loop detector for the loop system to Operate properly This is typically not a problem since most loop detectors have a very wide tuning range 20 2500 micro henries and can accommodate most size loops To calculate the inductance of a loop use this formula Side 1 Side 2 Side 3 Side 4 Number of Turns Inductance 2 Example To calculate the inductance of a typical 6 x 8 foot loop with four turns of wire 6 8 6 8 42 224 Micro Henries 2 Loop Info P 3 10 ED SECTION 1 HOW THE LOOP SYSTEM WORKS Field of Sensitivity A loop sets up an inductive field called a field of sensitivity This field of sensitivity completely surrounds the loop wires extending above below and on all sides of the loop When a vehicle or any metallic object enters this field of sensitivity the inductance of the loop changes as more of the inductive field is disrupted by the vehicle Once the disruption of the inductive field is high enough the loop detector senses this change and outputs a signal usually in the form of a dry contact relay switch activation Sensitivity Field Roadway lt e 3 Turn Saw Cut Loop
10. loop lead in wire connects There are also various other types of standalone detectors available on the market that can be hard wired into the gate operator control board that lead in wire be twisted a minimum of six turns per foot The lead in cable If additional lead in wire is required DoorKing recommends that you use a Shielded twisted pair Insulated floated at one end and grounded at gate opera tor with a direct burial rated jacket or be placed in PVC conduit All splices must be soldered and placed in a watertight J box Proper installation of the loops is essential for reliable functioning of the detector system Most detector problems are caused by improper loop installation The geometry size and shape of the loop defines the detection zone characteristics Loop size may vary and will depend on lane width traffic patterns and types of vehicles to be detected The short leg of any loop used for vehicle detection should never be less than 18 in The height of detection is directly related to the length of the short leg of the loop A general rule of thumb to follow is that the height of detection is 1 2 to 2 3 the length of the short leg of the loop Normal loops 4 ft x 8 ft are used to detect motorcycles and automobiles Minimum size for loops to detect typical vehicular traffic is 18 in x 48 in It is always recommended to use a larger loop whenever possible e Maximum detection height of a loop is 3 to 4
11. o R Loop Info P 3 10 Detection Field Around Loops It is important that the loops are installed far enough away from all moving metal objects gate to keep the loop s detection fields clear The 1 2 to 2 3 the length Mea of the short leg of the loop will determine a detection field limit Do not install the oop closer to the gate than the short leg of the loop otherwise the movement of the gate will interfere with the loop s detection field and the loop detector will Slide Gate give a false call and reverse the gate s direction in mid cycle A simplified solution is to place loops al LEAST 4 feet away from each other or the gate a ee aves a a a ie Vere Er eek ees as aca ea ec Lit ce RL MARE ane x ol r ee i sl I 5l ShortiLeg i Shot Leg I Distance Distance I a 5 na l shortLeg tomate rom aate 2 i IOnti I SI Length PO Optional ol Automatic a I a iExit Loop I Reverse l I l I I a Loop l l SI i I l i ai I i i l E R a ffi Loop Detection Field 1 Drawings not to scale L When loop detection fields overlap loop nor MUST be on different frequencies or they will cross talk See below Swing Gate When loop detection fields do not overlap loop detectors can be on similar frequencies l l l l l i l l l l l I a q I l
12. with HOT sealant that will encapsulate the wires and protect them from all moisture This wire is not rated for direct under ground burial and will absorb moisture if not completely protected by the hot sealant DO not use cold sealant with this type of wire because it will not completely encapsulate the wires Any voids in the sealant will allow moisture next to the wire insulation that can cause a loop failure in time Either type wire must be wound with one continuous length No splices are allowed Backer Rod The loop wires must be held securely in the bottom of the slot by means of a plastic foam type material called Backer Rod The recommended method of holding the loop wire in the slot is to use a series of one 1 inch long pieces of backer rod spaced approximately one 1 foot apart along the entire length of the saw cut and exit slot Make certain to press the backer rod tightly into the slot Use a wooden stick or other blunt instrument to avoid potential damage to the loop wire If the backer rod is not pressed tightly into the slot the loop wires will be loose in the slot and can cause false calls due to vibration or sudden movement Cold or Hot Sealants Cold sealant is typically preferred because it is easier to use than hot sealant It is pliable and will Give with tempera ture changes in the type of roadway used Typically asphalt or concrete When properly applied the cold sealant should completely cover the loop wires an
13. Cutaway of Underground Loop Inductive Field of Sensitivity The height of the field of sensitivity and therefore the height of detection is determined by the size of the loop The height of detection is especially important when you need to detect a high bed truck which requires more height than a passenger car The height of detection above and below the loop is determined by the shortest leg of the loop The height of detection is equal to 1 2 to 2 3 the length of the SHORT LEG For example a four foot by eight foot loop will give you approximately 2 1 2 feet of detection height whereas a six foot by eight foot loop will give you approximately 4 feet of detection height The short leg of a loop used for vehicle detection should never be shorter than 18 in The maximum detection height of a loop is 6 feet on the short leg If larger loops are used the detectable height of the loop will NOT increase Maximum Detection Height Detection Height Approx 4 ft Approx 3 ft Detection Height cas Loop Info P 3 10 Winding the loops in the same direction Clockwise or Counter Clockwise electrically creates the effect of the electrical current passing through the closest edges of the loops in opposite directions Since the electrical currents are flowing in the opposite directions the inductive fields of sensitivity created have the same magnetic poles North or South toward each other Since
14. EKS DOORKING INC Information Manual Underground Loops and Loop Detectors DoorKing Plug In Loop Detectors and Loop Accessories Copyright 2010 DoorKing Inc All rights reserved Underground Loop 2 Lead in Wire or Cable 2 Loop Detector 2 Design Facts 2 3 SECTION 1 HOW THE LOOP SYSTEM WORKS 4 Field of Sensitivity 4 Height of Detection 4 Field Cancellation Effect 5 Field Enhancement Effect 5 Loop Phasing 6 Electrically Reverse the Phase of a Loop 6 Loop Detection Field Interference and Loop Placement 7 SECTION 2 LOOP INSTALLATION GUIDELINES 8 Saw Cut Loop Guidelines 8 9 DoorKing Preformed Loop Guidelines 10 SECTION 3 TYPICAL LOOP LAYOUT EXAMPLES Ti Slide Gates 11 Swing Gates 12 SECTION 4 TROUBLESHOOTING LOOP SYSTEMS 13 Loop Diagnostics 13 Poor Connections 13 Shorted Loop Wire 13 Detector Adjustments 13 SECTION 5 DOORKING LOOP DETECTORS AND ACCESSORIES 14 Loop Info P 3 10 Sig INTRODUCTION A loop detection system is a method of sensing vehicles and is typically used in automated gate applications to prevent a gate from automatically closing on a vehicle or to automatically open the gate when a vehicle is exiting a property Vehicle loops can also be used to activate card readers ticket spitters etc When properly installed loops are an extremely reliable form of vehicle detection The loop detection system operates by creating an electrical field of sensitivity that tunes to the surrounding environment When
15. as been nicked and the integrity of the loop is questionable If the resistance is less than 50 megohms the loop wire will have to be replaced M500 Megohmmeter e Sensitivity sets how much moving metal must be present for the detector to send an output e Sensitivity Boost increases sensitivity by a factor of ten once a vehicle is detected This locks in high bed trucks e Frequency sets the operating frequency of the loop When two loops are operating in close proximity to each other the frequency on each detector should be set differently The loop with the longest length of wire should be set at the lowest frequency e Frequency Counter Blinks out frequency on L1 LED when the detector is powered up or reset button has been pressed Loop Info P 3 10 r 13 SECTION 5 DOORKING LOOP DETECTORS AND ACCESSORIES All loop detectors have the following features e Self tuning circuitry Automatically adjust for different loops and changes in weather e Sensitivity boost automatically increases sensitivity during detection Prevents dropout from high bed vehicles e Four frequencies available e Four sensitivity levels available e Surface mounted LED s to indicate when power is applied to the detector and when the loop is triggered Part Number Description 9410 010 Single channel plug in detector board Four different sensitivity and frequency settings Sensitivity Boost feature frequency counter and Fast Tra
16. d backer rod and level with the top of the roadway Since the sealant forms a barrier between the wire and the environment it is essential that the wires are completely covered There must be NO voids where water can collect and freeze within the slot The freeze thaw cycling will eventually push the loop wires up and out of the slot where the voids exist resulting in a loop failure Hot sealant must completely surround the loop wires and backer rod to protect them from moisture Very close attention must be paid with this type of installation because any voids in the sealant can allow moisture next to the wire insulation causing a loop failure in time Hard setting epoxies should not be used in softer material like asphalt Lead In Wire The lead in wire is a continuation of the loop wire No splicing and is typically used when the distance between the loop and the detector is 10 ft or less It must be tightly twisted together with a minimum of six turns per foot Lead In Cable If a lead in cable is used Typically for distances greater than 10 ft between the loop and the detector it should be a shielded twisted pair with a high density polyethylene insulation The shield should be floated left unconnected and insulated at the spliced end and grounded to an earth ground Operator s ground at the detector end Any other grounding arrangements can cause erratic system operation See page 6 Splice Connections 1 All splices must be soldered d
17. for easy maintenance Page 6 Automatic Exit Loop Install a separate loop detector Minimum loop size is 18 in x 48 in Pages 3 and 4 DoorKing preformed loops are 4 ft x 8 ft Page 10 Normally located 20 100 feet away from the gate so that the gate is open or opening as you drive up to it Typically a loop lead in cable will need to be installed Pages 2 and 6 Loop should to be far enough away from the reverse loop to avoid any cross talk or on a different loop detector frequency if detection fields overlap Reverse Loops Minimum loop size is 18 in x 48 in Pages 3 and 4 DoorKing preformed loops are 4 ft x 8 ft Page 10 Loops must be the same size same number of turns and same distance away from the gate Page 6 Loops must be wound in the same direction to create a Dead Zone Page 5 Loops must be wired in series Page 6 Loops must be far enough away from gate to avoid gate movement interference Page 7 Loops should to be far enough away from the exit loop to avoid any cross talk or on a different loop detector frequency if detection fields overlap Page 7 Loop Info P 3 10 Swing Gates Every swing loop installation is unique and may have specific problems that are not fully explained in this manual DoorKing highly recommends that the loop system is installed by a professional installer who understands loop systems and can foresee any problems that might occur for y
18. k feature Manufactured by DoorKing Inc 9409 010 Two channel plug in detector board Four different sensitivity and frequency settings for each loop Sensitivity Boost feature frequency counter and Fast Trak feature for each loop Loop 1 output is feed directly into control board loop two output is via a dry contact relay Manufactured by DoorKing Inc 9401 045 Megohm meter Checks integrity of ground loops Reads up to 500 megohms om Asphalt sealant flat black 10 oz tube 2600 72 Concrete sealant gray 10 oz tube 9401 060 Pre fabricated ground loop BLUE 24 foot circumference with 50 foot lead in cable Loop consist of three turns of THHN insulated 18 AWG stranded wire enclosed in PLIOVIC tubing allowing it to be formed to the size and shape required A T connector allows the lead in wire to be routed through a 1 2 inch PVC conduit 9401 061 Pre fabricated ground loop BLACK 24 foot circumference with 50 foot lead in cable Loop consist of three turns of THHN insulated 18 AWG stranded wire enclosed in PLIOVIC tubing allowing it to be formed to the size and shape required A T connector allows the lead in wire to be routed through a 1 2 inch PVC conduit 9401 062 Pre fabricated ground loop RED 24 foot circumference with 50 foot lead in cable Loop consist of three turns of THHN insulated 18 AWG stranded wire enclosed in PLIOVIC tubing allowing it to be formed to the size and shape required A T co
19. nnector allows the lead in wire to be routed through a 1 2 inch PVC conduit 18 AWG XLPE Loop Wire Order by Part Number 500 Feet P N 9402 076 P N 9402 078 P N 9402 080 1000 Feet P N 9402 077 P N 9402 079 P N 9402 081 Loop Info P 3 10 Information Manual Underground Loops and Loop Detectors DoorKing Plug In Loop Detectors and Loop Accessories DOORKING INC DoorKing Inc 120 Glasgow Avenue Inglewood California 90301 U S A Phone 310 645 0023 Fax 310 641 1586 Loop Info P 3 10 www doorking com
20. o not use wire nuts or crimp connectors because the output from the loop detector to the loop is at very low voltage This means that there is not enough power to go through a weak connection 2 Each splice point must be protected with a moisture proof seal No splices are allowed in the loop itself Failure to observe these precautions are the two most common causes of loop related problems Exit Slot Where the loop wires leave the loop saw cut NO sharp angles they must be tightly twisted together with a minimum of six turns per foot Use tape on the twisted end to hold the wires together This prevents false calls from movement between the wires ecm Loop Info P 3 10 Cutaway of Underground Loops Roadway Sealant even with road surface Sealant even with road surface Sealant 1 2 to 3 4 Min Sealant gt 1 depth Backer Rod He 1 Foam backer rod 5 Bi sed ho Typical spaced every 1 ft in saw cut Depth will vary Typical QO number of wire O turns e meee 3 16 to 1 4 Saw Cut e 3 16 to 1 4 Saw Cut 4 Turn Loop or Greater 3 Turn Loop or Less Drawings not to scale DO NOT allow the straight saw cuts to connect in the corners or the triangular roadway pieces that are created will eventually break free from the roadway NO 90 Elbows Note Use only sweeps for 90 conduit bends Do not use 90 elbows as this will make wire pulls very difficult and can cause damage to wire insulation
21. our specific installation Swing gates typically use two reverse loops that are installed outside the swing path of the gate This is necessary to avoid the loops detecting the gate swinging over them This would be detected by the loops and cause the gate to reverse However this leaves a large unprotected area To eliminate the unprotected area a shadow loop is installed under the swing path of the gate The control circuit in the jaa operator will only accept inputs from the shadow loop detector when the gate is in the full open position Once the gate begins its closing cycle the gate Operator ignores any input from the shadow loop detector thereby allowing the gate to pass over the shadow loop without reversing itself The reverse loops and shadow loop require a two channel loop detector The optional automatic exit loop requires a separate single loop detector Reverse Loops Shadow Loop Minimum loop size is 18 in x 48 in Pages 3 and 4 DoorKing preformed loops are 4 ft x 8 ft Page 10 Minimum loop size is 18 in x 48 in Pages 3 and 4 Loops must be the same size same number of turns and same distance away from the gate Page 6 DoorKing preformed loops are 4 ft x 8 ft Page 10 Loops must be wired in series Page 6 Loop should stay inside swing path of gate Loops must be far enough away from gate to avoid gate movement interference Page 7 Loop should line up with open gate position Loops should to
22. ow the surface of the pavement The saw cut must be free from loose debris which can damage the wire insulation If the saw cut is too deep the roadway under the saw cut may crack over time creating a possible path for water into the road bed material One guideline to consider would be to try not to exceed 50 of the overall pavement depth when cutting a slot for the loop wire Greater depth should be used in softer pavement materials to protect the loop wire against damage from surface erosion and wear Shape of Loop The loop is typically cut in a rectangle with 45 angled corners that eliminates the sharp edges that can eventually cut through the wire insulation DO NOT allow the rectangular saw cuts to connect in the corners or the triangular pieces that are created will eventually break free from the roadway Cut an exit slot with NO sharp angles for the wires where they leave the loop saw cut Types of Loop Wire Moisture in the loop s wire insulation can cause significant changes in the dielectric constant resulting in excessive loop frequency drift Choose a wire insulation that is impervious to moisture Typically 18 AWG Cross Linked Polyethylene XLPE insulated wire is used with COLD sealant because of the ease of installation It is rated for direct underground burial which makes it very resistant to moisture absorption and provides good abrasion resistance 18 AWG Polyvinyl Chloride PVC insulation TFFN THHN THWN should ONLY be used
23. p will false call or lock on Often a crimp connection wire nut or similar type connector will operate when they are originally installed but after a period of time the wires may corrode or the connection will loosen Vibrations from gate operators can cause these loose connections to be intermittent and generate false calls or lock up the detector Remember the power through the loop is very low and does not have enough power like 110 volt connection to go through any type of corrosion or loose connection Be sure that all connections are soldered The loop wire shorting to ground is a very common problem This is especially true when PVC wire THHN TFFN etc is used for the ground loop or a splice was made underground These type of problems will often cause problems when moisture is present If there is a nick in the wire insulation the loop will work when the ground is dry but when moisture is present rain sprinklers morning dew etc the nick causes a short to ground This can be checked by utilizing a megohm meter capable of testing up to 500 megohms 500 million ohms such as a DoorKing meter P N 9401 045 A typical ohms meter will not read units as small as micro henries Disconnect the loop wires from the loop detector Place one of NOL the meter leads to the loop wire and the other to earth ground Resistance should be greater than 100 megohms If resistance is between 100 and 50 megohms the wire insulation h
24. re from Loop Shielded twisted pair witha high density polyethylene insulation PVC Conduit Tape to keep Watertight J Box wires together All spliced connections must be soldered Do not use wire nuts or crimp connectors Phasing loops refers to the direction that the electrical current flows through the loops and not necessarily the physical direction that the loop wire has been wound For example if two loops are installed and physically wound in a Clockwise direction you can reverse the electrical current through one of the loops by simply reversing the connection where the loops are wired together Doing this effectively changes the electrical direction that the loops are wound Loop 1 physically wound clockwise Reverse the loop 2 wires to reverse the electrical direction Phase of loop 2 Loop 2 will then function in a counter clockwise electrical direction Loop 2 physically wound clockwise Operator Chassis Ground If using shielded twisted pair loop lead in cable ground shield at operator end ONLY Note If slide gate reverses direction during cycling without an obstruction present vehicle on loop loop sensitivity fields might be attracted to each other and sensing the gate s movement Electrically reversing one loop would change the field of sensitivity allowing a Dead Zone for gate movement ne a
25. together for easy maintenance Page 6 frequency if detection fields overlap Page 7 Loop Info P 3 10 SECTION 4 TROUBLESHOOTING LOOP SYSTEM Proper installation of the loops is essential for reliable functioning of the detector system Loop detection systems when properly installed will provide one of the most reliable forms of vehicle detection available Many loop system problems are caused by poor connections splices incorrect type of loop wire or the loop wire shorting to ground all of which will cause intermittent operation or complete failure DoorKing loop detectors have a provision that provides loop diagnostics which identifies if a problem has occurred in the detection system The red surface mounted LED L1 on the loop detector will illuminate when the detector senses a vehicle presence and will go out when the vehicle ays o if vlu LOOP 1 TE E E of the connections this LED will go into a fault mode by flashing If the problem is a short or an intermittent poor connection which corrects itself the detector will return to normal operation however the LED will continue to blink until it is manually reset or until power is removed from the system If the LED is blinking even if the detector is working properly a problem exists and checks should be made for poor connections or shorts to ground A poor connection from the loop to the loop detector will generally cause an intermittent problem where the loo
26. ver the two inside wires decreases as the loops are moved closer together and increases as the loops are moved apart Loop wound Clockwise Inside Outside Wire Field Wire Field Counter clockwise Loop Clockwise Loop Loop wound Counter Clockwise 2 loops wound in opposite directions attract the inside wire fields Loop Info P 3 10 aD It was mentioned previously that when two loops are wired to the same detector terminal they must be the same size same number of turns and the same distance from the gate They must be connected in series and the direction in which each loop is wound is important for proper door or gate operation It is also advisable to have the loop connections accessible for mainte nance and repair Route each of the loop lead in wires all the way to the loop detector before wiring the loops together in series for easier access to the loop connections in future maintenance rather than connecting them together in a water tight junction box in the ground and running a single lead in cable to the loop detector F ay Terminal 7N H D O O PVC Conduit Loop 1 Wound Clockwise Tape to keep wires together 2 loops i wired in series at the loop PVC Conduit Loop 2 Wound Clockwise detector Loop lead in wires running to loop detector Must be twisted a minimum of six turns per foot Loop Lead in Cable Insulated Floated Shield Soldered Connection Wi
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