Strong Motion Accelerometer User`s Manual Revision 2.01 June 2015
Contents
1. Wire 1 Pair 9 Enable Return U Wire 1 Pair 9 CB CB White White Wire 1 Pair CAL Input Vv Wire 1 Pair 10 CB 10 CB Black Black Wire 2 Pair CAL Input W Wire 2 Pair 10 CB 10 CB Brown Brown Wire 1 Pair RS 232 TX X NC Triad Red 11 CB Wire Black Wire 2 Pair RS 232 RX Y NC Triad Black 11 CB Red Wire Wire 2 Pair 9 RS 232 GND Z NC Triad White CB Gray Wire 1M to Power Bundle a Power Bundle Shield Power Shield CASE Ground Drain Wire Bundle Shield Drain Wire Wire 1 Pair Input Power b Wire 1 Pair 12 PB 12 PB 9 36V Black Black Wire 2 Pair Input Power Return c Wire 2 Pair 12 PB 12 PB Orange Orange Triad Shield Drain Wire NC NC Table 2 Connection details of standard 6 meter cable EpiSensor2 User s Manual June 2015 Operational Control of the EpiSensor2 The sensor can be controlled in multiple ways button pushing local digitizer enable lines remote and RS 232 local and or remote Using either of these the operator can control the full scale range and AUTOZERO state of the sensor Using the digitizer or RS 232 interfaces the user can control a complete calibration CAL capability Using a dedicated digital line connected to the digitizer the operator can issue a RESET to the sensor that is similar to a Power ON RESET Finally the user can use the RS 232 interface to communicate with the sensor to receive a variety of sensor2. 0 5g Asserting the line for between 0 5 and 1 5 seconds places the sensor range at 0 25 Mo Wilh RS 232 Command Line Interface 1 At the MAIN prompt enter enable12345 to allow access to command menus 2 Type OPERATE to select OPERATE page 3 At the OPERATE prompt type command to select range 1 4g for 4g Page 10 of 16 EpiSensor2 User s Manual June 2015 2g for 2g 1g for 1g 0 5g for 0 5 0 25g for 0 25 Cie tS Range Signaling The EpiSensor2 feeds a range dependent signal into the the low resolution mass position channels of the Q330 5V 50 counts for 4g range AV 50 counts for 2g range 3V 50 counts for 1g range 2V 50 counts for 0 5g range 1V 50 counts for 0 25g range In addition the Episensor2 outputs a coded range signal on to each of the channels SIGNAL line 5 pulses for 4g range 4 pulses for 2g range 3 pulses for 1g range 2 pulses for 0 5g range 1 pulse for 0 25 range This is output at power ON following a RESET event and following any range setting activity Typical pulses for 4g range are shown in Figure 4 ae EE es F 1534 QuickView Se Channels to Disph M Scale Lock a I Chi f Ch2 Ch Meh Coch che yp fd Channel 1 RMSmv 113 87803 AVGmV 28 6 WIN 19660800 Channel 2 RMSmV 113 92287 WIN 19660800 Channel 3 RMSmV 113 41725
3. AVGmV 23 0 WIN 19660800 Duration FL Close 10 Seconds of data G HOE C 30s C 60s C 120s Figure 4 Pulse train range signal for 4 g range Page 11 of 16 EpiSensor2 User s Manual June 2015 AUTOZERO The EpiSensor2 has an autozero capability that will remove DC offsets from the signal up to an acceleration equivalent limit of 100 mg Autozero operates simultaneously on all three channels There are only two modes ON and OFF The current state is stored in non volatile memory The sensor will enter the appropriate state after a POR event There are three ways to control the autozero state Button Pushing 1 Press the button once for about 1 second 0 2 to 2 second acceptable window This will light the LEDs and enable the system 2 Push and hold the button for between 5 and 10 seconds to toggle the AUTOZERO ON OFF A green LED will be lit when AUTOZERO is ON 3 After 30 seconds of inactivity the LEDs will shut off and the system will be disabled 0330 Enable Lines Q330 used for this description 1 The sensor monitors Q330 Generic Enable line 1 2 Apulse length encoding scheme is used to set the AUTOZERO state 1 Asserting the line for between 1 and 3 seconds turns AUTOZERO ON 2 Asserting the line for between 4 and 6 seconds turns AUTOZERO OFF RS 232 Command Line Interface 1 At the MAIN prompt enter enable12345 to allow access to command menus 2 Type OPERATE to select OPERA
4. 1 SB SB Black Black C NC Signal Bundle Shield C Signal Bundle Shield Drain Wire D Wire 1 Pair 2 Y Acceleration D Wire 1 Pair 2 SB SB White White E Wire 2 Pair 2 Y Acceleration E Wire 2 Pair 2 SB SB Brown Brown F NC Control Bundle F Control Bundle Shield Shield Drain Wire G Wire 1 Pair 3 X Acceleration G Wire 1 Pair 3 SB SB White White H Wire 2 Pair 3 X Acceleration H Wire 2 Pair 3 SB SB Red Red J NC J NC K Wire 1 Pair 5 Z Channel Range K Wire 1 Pair 5 CB CB White Indicator White L Wire 2 Pair 5 Y Channel Range L Wire 2 Pair 5 CB CB Yellow Indicator Yellow M Wire 1 Pair 6 X Channel Range M Wire 1 Pair 6 CB CB White Indicator White NC wire Wire 2 Pair 6 NC wire Wire 2 Pair 6 CB floats CB Green floats Green N Wire 1 Pair 4 ANALOG Ground N Wire 1 Pair 4 SB SB White White NC wire Wire 2 Pair 4 NC wire Wire 2 Pair 4 SB floats SB Orange floats Orange P Wire 1 Pair 7 CAL Enable Line P Wire 1 Pair 7 CB CB White Logic Level White R Wire 2 Pair 7 AUTOZERO Enable R Wire 2 Pair 7 CB CB Blue Line Blue Logic Level Page 8 of 16 EpiSensor2 User s Manual June 2015 Wire 1 Pair 8 RESET Enable Line S Wire 1 Pair 8 CB CB White Logic Level White Wire 2 Pair 8 RANGE Enable Line T Wire 2 Pair 8 CB CB Violet Logic Level Violet
5. Manual June 2015 Setup and Initial Operation The EpiSensor2 should be placed on a firm surface The sensitive directions X and Y are aligned with the sides of the sensor The sensor should be leveled using the threaded adjustment feet and the bubble level One of these feet is shown in Figure 5 Following leveling the feet can be locked by tightening the lock nut up against the bottom of the sensor finger tight only The central bolt hole can be used to anchor the sensor to the mounting surface This can use bolts and a threaded insert in the surface or a threaded stud that passes up from the surface to be captured with a nut Connect the sensor cable to the sensor and to the digitizer Q330 series or Rock series The sensor will power ON over the course of a few seconds The current range and current AUTOZERO status ON or OFF will be signified by the LEDs Wait until the LED extinguishes about 30 seconds Pressing the LED once for between 0 2 and 2 seconds will re illuminate the LED It will also activate the button system for further control discussed below Upon power up the sensor will output an analog signal on its range indicator lines These will be recorded by the digitizer The use can verify the current range setting by monitoring these values or by analyzing the pulse train sequence shown in Figure 4 At this point the sensor is operational LOCKING NUT Figure 5 Details of leveling feet Page 14 o
6. provides a complete set of electronically controlled operational modes including range switching allowing 4g 2g 1g 0 5g and 0 25g full scale ranges Offset removal AUTOZERO mode and calibration These modes can be controlled remotely either via the digitizer using selected enable lines or via an RS 232 command line interface The sensor also provides a pushbutton switch for local control This allows an on site user to select sensor full scale range and AUTOZERO state ON or OFF An important feature of the EpiSensor2 is its very low quiescent power consumption under 350 mW The sensor consumes 60 to 70 lower power than competing strong motion accelerometers This makes it ideal for remote battery powered applications The EpiSensor2 and its cabling are designed for direct connection to Quanterra Q330 series digitizers as well as digitizers from the Kinemetrics Rock series The EpiSensor2 module and some of its features are shown in Figure 1 PUSHBUTTON SWITCH KKK KINEMETRICS AUTOZERO LED j EpiSensor2 BUBBLE Lever 4 INPUT CONNECTOR Figure 1 EpiSensor2 module Page 3 of 16 EpiSensor2 User s Manual June 2015 Electrical Connections The EpiSensor2 contains a Souriau connectoron its side The connections supported by this receptacle are shown in Table 1 851 07C16 26P50 A7 44 Receptacle Sign
7. sensor is generally expected to come from the digitizer via pins b and c The connections within the standard cable PN Epi2 0 320001 6 are listed in Table 2 For users wishing to create their own cables Kinemetrics can supply a standard right angle solder cup plug with cable clamp that will connect directly to the EpiSensor2 The commercial part number for this item is Souriau 851 08EC16 26S50 44 This plug and the connection details in Table 1 are all that users will need to make connection to the sensor Please contact Kinemetrics to discuss specific cable requirements and details Page 6 of 16 EpiSensor2 User s Manual June 2015 DIGITIZER PLUG 16 SHELL SOURIAU RS 232 PLUG 10 SHELL SOURIAU Epi2 0 320001 6 STANDARD VAULT CABLE 6 METER LENGTH Figure 2 Sensor with standard cable Epi2 0 320002 1 5 a j l j i RS 232 CABLE Li CONNECTED TO STANDARD CABLE PLUG Figure 3 Standard cable with RS 232 cable connected Page 7 of 16 EpiSensor2 User s Manual June 2015 Inbound Outbound Outbound End End End Sensor Recorder RS 232 Connector Connector Connector 851 08E16 Conductors Signal 851 06E16 Conductors 851 06E10 Conductors 26850 44 RA 26P50 44 98S50 44 Plug Plug Plug A Wire 1 Pair 1 Z Acceleration A Wire 1 Pair 1 SB SB White White B Wire 2 Pair 1 Z Acceleration B Wire 2 Pair
8. Kinemetrics EpiSensor2 Strong Motion Accelerometer User s Manual Revision 2 01 June 2015 KINEMETRICS Kinemetrics Inc Pasadena CA USA www kinemetrics com Page of 16 EpiSensor2 User s Manual June 2015 No User Serviced Parts The EpiSensor2 is a self contained seismic accelerometer There is no reason to open the sensor package or to modify the electronics or sensor elements contained within it There are no internal manual adjustments to make to nor are there any user serviced parts within the sensor Opening and or modifying the sensor is unnecessary and doing so will void the instrument s warranty Electrical Safety Notice As with all electrical instruments potentially lethal potentials can be present on all metal surfaces including conductors within any cables Proper grounding of these elements is important to minimize these risks The user of this product is responsible for its installation and operation in a safe manner and in accordance with all local requirements for electrical safety Page 2 of 16 EpiSensor2 User s Manual June 2015 Introduction and Product Description The EpiSensor2 is an advanced force balance triaxial accelerometer that builds upon the outstanding record of its predecessor the EpiSensor the world s first seismological grade strong motion accelerometer The high dynamic range of the EpiSensor2 allows both weak and strong motion recording from a single sensor The EpiSensor2
9. TE page 3 At the OPERATE prompt type command to select range 1 AUTOZEROON turns ON Autozero 2 AUTOZEROOFF turns OFF Autozero Page 12 of 16 EpiSensor2 User s Manual June 2015 CAL Calibration The EpiSensor2 allows the injection of external calibration signals into the sensors All three axes are excited simultaneously There is a green LED that signals whether CAL is ENABLED or DISABLED There are two ways to control the CAL state 0330 Enable Lines Q330 used for this description 1 The sensor monitors Q330 CAL_ENABLE line 2 Asserting the line enables CAL Signals presented at the CAL input pins of the connector will be injected into the calibration circuit of the sensor 3 De asserting the line disables CAL 4 The sensor operates seamlessly with the standard Start Stop Sensor Calibration commands in Willard RS 232 Command Line Interface 1 At the MAIN prompt enter enable12345 to allow access to command menus 2 Type OPERATE to select OPERATE page 3 At the OPERATE prompt type command to select range 1 CALON enables CAL 2 CALOFF disables CAL RESET Asserting the Q330 Generic Enable 2 AUX 1 line rests the sensor It effect is equivalent to a Power ON RESET POR event without interrupting the power STATUS Reports Each RS 232 Command Line Menu supports a status command These print out a set of menu specific information Page 13 of 16 EpiSensor2 User s
10. al Notes Pin Designator A Z Acceleration B Z Acceleration C Shield Connection Connected to ANALOG Ground D Y Acceleration E Y Acceleration F Shield Connection Connected to ANALOG Ground G X Acceleration H X Acceleration J Shield Connection Connected to ANALOG Ground K Z Channel Range Indicator L Y Channel Range Indicator M X Channel Range Indicator N ANALOG Ground P CAL Enable Line Logic Level R AUTOZERO Enable Line Logic Level S RESET Enable Line Logic Level T RANGE Enable Line Logic Level U Enable Return Vv CAL Input W CAL Input X RS 232 TX Page 4 of 16 EpiSensor2 User s Manual June 2015 Y RS 232 RX Z RS 232 GND a Power Bundle Shield CASE Ground b Input Power 9 36V c Input Power Return Table 1 Connections to sensor through Souriau 851 07C16 26P50 A7 44 receptacle Note that the shield connections pins C F and J are provided for redundancy in specially designed cables Within standard sensor cabling these connections are not propagated into the cables at the sensor end Rather the shield connections are made only at the digitizer end of the cable The digital enable lines P R S T relative to U are fully isolated from other lines in the system They operate over an approximate 2 9V input range The RS 232 interface on pins X Y and Z is fully isolated as well The power inputs pins b and c work over a range of 9 36V at the sensor inpu
11. f 16 EpiSensor2 User s Manual June 2015 Operational Details Choice of Digitizer The instantaneous dynamic range of the sensor is greater than any modern seismic digitizer particularly when operating on the 4g and 2g ranges 26 bit digitizers such as the Q330HR are preferred for utilizing the greatest part of this range More conventional 24 bit digitizers also work well however the self noise of a properly installed sensor is well below that of the input noise of the digitizer Some digitizers provide integrated preamplifiers While these are useful for investigation of the exact levels of sensor self noise their use will greatly reduce the full scale range of the sensor This effectively defeats the purpose of a strong motion accelerometer Typically the best system performance will be achieved by use of a Q330HR 26 bit digitizer with its preamplifiers OFF Full Scale Range Selection Sensor dynamic range is typically highest on the highest full scale range settings 4g and 2g where the 1 Hz dynamic range is in excess of 160 dB However sensor self noise typically drops with range setting although noise on 0 5g and 0 25 g ranges are practically identical The choice of peak full scale range should ensure that there is near zero chance of clipping due to maximal local signals Users should select ranges above the maximum expected signal AUTOZERO Mode The AUTOZERO system records and corrects the sensor offsets in sit
12. n the Page 15 of 16 EpiSensor2 User s Manual June 2015 sensor These settings are updated whenever the status is changed by the user or the digitizer Upon a system POWER ON RESET or simple RESET the sensor is restored to the previous operating configuration The calibration status however is volatile Following any RESET event the calibration mode must be re entered using either the digitizer enable line or an RS 232 command Sensor Response Values Each sensor element is trimmed during manufacture to provide a standard scalar response Volts g on each of the five operating ranges In addition each sensor axis is trimmed to ensure that its response bandwidth falls within a set range 3 dB point at or above 320 Hz The scalar responsivity G is stored on the RESPONSE page that is described below A command query on this page status command will return the scalar response values for each element at the current full scale range setting The Episensor2 frequency response can be described well by a simple set of conjugate pole pairs P1 700 1250j radians second P2 1340 3350j radians second The full response is defined as Vo G_ P1 P2 s P1 s P1 s P2 s P2 where G is the scalar responsivity Volts m Input Power Rquirements RS 232 Command Line Interface Page 16 of 16 EpiSensor2 User s Manual June 2015
13. specific information serial numbers scalar response values etc The RS 232 command line menu is discussed further below Full Scale Ranges The EpiSensor2 supports five digitally selectable ranges with nominal scale factors Range 5 4g 5 V g Range 4 2g 10 V g Range 3 1g 20 V g Range 2 0 5g 40 V g Range 1 0 25g 80 V g There are red LEDs that show the current range This range is stored in non volatile memory The sensor range will be maintained upon a power on reset POR event There are three methods for setting the range Button Pushing 1 Press the button once for about 1 second 0 2 to 2 second acceptable window This will light the LEDs and enable the system 2 Each subsequent button push changes the range by one step in a cyclical fashion Wait about 5 seconds between subsequent pushes 3 After 30 seconds of inactivity the LEDs will shut off and the system will be disabled Digitizer Enable Lines Q330 used for this description 1 The sensor monitors the Q330 s Generic Enable line 3 AUX 2 2 Apulse length encoding scheme is used to select the range 1 Asserting the line for between 4 5 and 5 5 seconds places the sensor range at 4g Asserting the line for between 3 5 and 4 5 seconds places the sensor range at 2g Asserting the line for between 2 5 and 3 5 seconds places the sensor range at 1g Asserting the line for between 1 5 and 2 5 seconds places the sensor range at
14. t This galvanically isolated input has reverse polarity protection as well as overcurrent protection The ANALOG ground line Pin N is the common mode voltage reference for the differential signal lines pins A B D E and G H It also serves as the reference ground for the range voltage signals pins K L and M The calibration CAL input pins V and W is differential with a 15V range The common mode reference for these signals is ANALOG ground pin N Page 5 of 16 EpiSensor2 User s Manual June 2015 EpiSensor2 Cabling The standard cable for the EpiSensor2 is shown in Figure 2 This 6 meter long cable PN Epi2 0 320001 6 connects to the sensor and to the digitizer The 10 shell plug in the Y extension at the digitizer end is dedicated for the isolated RS 232 connection Kinementrics can also supply a simple RS 232 connection cable PN Epi2 0 320002 1 5 It connects as shown in Figure 3 to the 10 shell plug Among other cable options are ones without the RS 232 takeout This can be used when RS 232 control is not desired or when the cable run is beyond the practical limit of RS 232 communications typically 15 meters Kinemetrics can also supply pigtailed connectorless cables The maximum cable length is at or about 125 meters owing to limitations related to digitizer power sourcing mainly its voltage and series resistance in the power lines contained within the cabling Operating power for the
15. u This correction cancels fixed mechanical offsets in the sensor element as well as tilt related offsets due to sensor mounting It injects a separate feedback current that is automatically generated to cancel the observed offset AUTOZERO is either OFF standard mode or ON Any time that the sensor is RESET or it experiences a Power ON RESET or the AUTOZERO is explicitly set via the various control interfaces the sensor re calculates and corrects its offsets When continuously powered the sensor retains the same offset removal current setting AUTOZERO requires higher quiescent power consumption about 120 mW extra and it increases self noise levels Unless the user has special requirements e g very low dynamic range digitizer requiring the use of input preamplifiers Kinemetrics recommends leaving the AUTOZERO in its OFF state Any modern digitizer as well as many data analysis algorithms are not affected by DC offsets in the signals or in the digital data Calibration CAL Calibration is seamlessly supported through the digitizer connection This includes a digital control line for connecting the differential calibration input signals to the sensor elements and use of the voltage sources provided by the digitizer For the EpiSensor2 with DC 320 Hz bandwidth random noise is an excellent calibration stimulus source Retention of Settings The current full scale range and AUTOZERO status ON or OFF is stored in EEPROM withi
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