SGA AC/DC Powered Signal Conditioner Set Up
Contents
1. 05 07 SGAv2 5 13 61a 17 Chapter 6 Product Care A worn out component excessive use in harsh environments an overly zealous operator regrettably some circumstances necessitate repair Detailed below is our pledge to you a defined set of ground rules and procedures to which we will adhere All we ask in return is that you assist us with our procedure such that we can maintain our promise to you Please note that warranty repairs may not be available on overdue accounts and that a strict interpretation of our conditions of trading invalidates warranty claims where late payment has occurred In the unlikely event you have problems with the SGA module we would advise that you take the following precautions e The unit is installed as instructed e Recommended spares are kept in stock We can assist e Sufficient expertise available for first line maintenance e Routine maintenance checks are performed annually is recommended e The necessary documentation for the product is available to the maintenance personnel We recommend you keep on file as a minimum e This Manual e The settings of the switches and links on the SGA card e The calibration figures for the attached sensors e The instrument loop to which the output is connected e Arecord of the normal output if applicable e Amaintenance record of the SGA e Acontact phone number from the supplier for assistance 18 SGA User Manual 06 05 07 SGAv2 5 13 61a Cha2. pressure torque or load The SGA is designed to convert this change to a proportional electrical signal Torque Transducer The Torque Transducer is one of a series of STRAIN GAUGE sensors that the SGA input is designed to accept Torque Sensor Load Cell and Temperature transducers Zero is otherwise identified as Offset It relates to the proportional output to the sensor input Calibration of the SGA is determined by setting the Span Gain and Zero Offset Zero Adjustment The ability to adjust the display of a process or strain meter so that zero on the display corresponds to a non zero signal such as 4 mA 10 mA or 1V dc 20 SGA User Manual 06 05 07 SGAV2 5 13 61a given by a measuring instrument See Zero Suppression Zero Suppression The span of the SGA can be offset from zero zero suppressed such that neither limit of the span will be zero For example an SGA which measures a load of a 100kg span from 400kg to 500kg is said to have 400kG zero suppression IP66 UK Environmental Specification Hz kilohertz Frequency mi illi ane a E SC T Signal Conditioner SGA Strain Gauge Amplifier V Vots 0 0 mV millivolts SGA User Manual 06 05 07 SGAv2 5 13 61a Chapter 8 Specifications for SGA Load Cell Amplifiers Parameter NR Typical Max Unts Power supply SGA 110 230Vac 50 60Hz 110 230 vac Powersupplyde tt 24 vDC Semote Power supply curr
3. 10 volts symbol mV NEMA 4 UL Type 4 A standard from the National Electrical Manufacturers Association which defines enclosures intended for indoor or outdoor use primarily to provide a degree of protection against windblown dust and rain splashing water and hose directed water Noise An unwanted electrical interference on the signal wires Null A condition such as balance which results in a minimum absolute value of output Offset Offset is otherwise identified as Zero It relates to the proportional output to the sensor input Calibration of the SGA is determined by setting the Offset Zero and Gain Span Potentiometer Two potentiometers variable resistors are used in the SGA for fine calibration Pressure Transducer The Pressure Transducer is one of a series of Strain Gauge sensors that the SGA input is designed to accept Torque Sensor Load Cell and Temperature transducers Proportional Outputs The Voltage or Current outputs are calibrated to be directly proportional to the input from the sensor The output is within the sensor limits taken as linear and no linearity compensation is required within the SGA Resolution The input corresponding to a one unit change in the least significant digit of the data acquisition display O Good resolution is not necessarily equal to good accuracy Sensing Element That part of the transducer which reacts directly in response to the input Sensitivity The minimum change in
4. 5V Output Output E E P I a O a Lae Sw 2 a E Do not terminate shield at transducer end Excitation Strain Excite is the Excitation to the transducer Strain Input is the Signal from the transducer The Ref 5V 2 5V is generated internally and used for calibration The cable connecting the sensor to the SGA should be shielded This typical cable data is provided for information only The cable should have 2 x twin twisted cables ideally with each pair individually shielded and with an overall shield Table 2 1 Country Supplier PartNo Description UK Farnell 148 539 Individually shielded twisted multipair cable 7 0 25mm 2 pair Tinned copper drain Individually shielded in polyester tape Diameter 4 19 mm Impedance 54 Ohms Capacitance m core to core 115 pF amp core to shield 203 pF UK Farnell 585 646 Individually shielded twisted multipair cable 7 0 25mm 3 pair Tinned copper drain Individually shielded in polyester tape Diameter 6 86 mm Impedance 62 Ohms Capacitance m core to core 98 pF amp core to shield 180 pF UK RS 367 533 Braided shielded twisted multipair cable 7 0 2mm 1 pair Miniature twin round Diameter 4 8 mm Impedance 62 Ohms Capacitance m core to core 120 pF amp core to shield 210 pF If possible segregate the signal cable from Power Cables allow a 3 foot 1meter distance from such cables Do not run signa
5. SGA User Manual 06 05 07 SGAv2 5 13 61a Chapter 4 Calibration The SGA provides the excitation supply and signal conditioning to cater for a wide range of strain gauges load cells pressure transducers or torque transducers Output Select the analog output range as detailed in Chapter 3 Figure 3 1 Tables 3 1 amp 3 2 by means of SW4 Zero Offset Select the offset as detailed in Chapter 3 Table 3 9 by means of SW2 Having selected the polarity and the offset nearest to that required with the switches use the fine potentiometer P2 to achieve the final setting Sensitivity Select the sensitivity as detailed in Chapter 3 Table 3 6 by means of SW1 Switches 1 4 of SW1 provide fine setting of the SGA sensitivity while switches 5 7 give coarse control This arrangement allows the SGA to cover a wide range of strain gauge sensitivities without sacrificing stability and ease of set up Locate the required sensitivity in the table and set switches 1 7 of SW1 accordingly Potentiometer P1 provides fine trimming and range overlap to enable the SGA to be calibrated precisely to any given value within its ranges Note 1 If the range is repeated in the table e g 4mV V 4 0 4 05 and 4 0 mV V choose the setting which has the greatest number of switches 1 4 set to off i e SW1 1000 000 This will enable finer trimming to the final value using potentiometer PI The sensitivity settings shown in Table 3 6 assume that the load cell is ful
6. input signal to which an instrument can respond This is the relationship between the change in strain gauge output to the level or magnitude of the SGA output Signal Conditioner A circuit module that offsets attenuates amplifies linearizes and or filters the signal for input to an A D converter A typical output signal conditioning is 4 to 20 mA The SGA is essentially a Signal Conditioner more specifically known as a Strain Gauge Amplifier in that it conditions alters the input signal from a load cell to an electrical output Single card assembly The SGA has only the one Printed Circuit Board assembly on which all the components are mounted The assembly is then mounted inside an environmentally rugged enclosure Span is otherwise identified as GAIN It relates to the proportional output to the sensor input Calibration of the SGA is determined by setting the Span Gain and Zero Offset Span Adjustment The ability to adjust the gain of a process or strain meter so that a specified display span in engineering units corresponds to a specified signal span For instance a display span of 200 F may correspond to the 16 mA span of a 4 20 mA transmitter signal Stability The quality of an instrument or sensor to maintain a consistent output when a constant input is applied Strain Gauge The strain gauge is a resistance bridge device where the bridge value alters linearly and proportionally to the force exerted on it be it temperature
7. its packing Check that the unit is complete and undamaged The SGA unit can be operated in any industrial environment providing the following limits are not exceeded Operating Temperature 10 2C to 50 9C Humidity 9596 non condensing Storage temperature 10 C to 50 9C While the unit is sealed to IP65 NEMA 4X it is advisable to follow the following installation practice where possible Minimize vibration Do not mount next to strong electrical fields transformers power cables Ensure easy access to interior of the module Install electrical protection device as the unit is not internally fused Always ensure the lid is properly fitted and all 4 screws tightened Always ensure the cable gland is sealing against the cable to maintain the IP NEMA rating Figure 2 1 Dimensions 160mm 6 5 148mm 5 Allow for cable entry 80mm oa 90mm Mounting Holes 3 8 0 187 Depth 55mm 2 16 Sum The 4 screws for the lid are captive and must be tightened to maintain the seal The holes for the mounting screws in the base are directly behind the screws for the lid The box must not be drilled as this would invalidate the IP rating Allow sufficient space at both sides for the cable entry The Nylon 66 cable glands are designed for ROUND cables The waterproof entry and strain relief will seal to a higher rating than the enclosure Cable diameter should be between 4mm 0 16 and 7mm 0 27 SG
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9. 5V 2 5V E Strain Input Strain Gauge Output T mV Source 1 The Ref 5V 2 5V should be connected to Strain Input and the mV source applied between Strain Input amp Strain Input 2 Set the correct switch settings on SW1 as described above using the transducer s calibration sheet supplied by the manufacturer This is normally specified as sensitivity or full range output and should be in mV V 3 Ensure the Zero and Span switch settings are correct as detailed in Chapter 3 Tables 3 6 amp 3 9 4 Apply the known low calibration conditions and fine adjust P2 5 Apply the known high calibration conditions and fine adjust P1 6 Repeat steps 3 and 4 until the required output is achieved Hint If the required output at the low calibration point is OV and the required output at the high calibration point is 7 5V adjust P1 in step 5 to produce a change of 7 5V between the calibration points Initially the low calibration point may not produce 0V at the output If this is the case note the reading e g 0 5V apply the high calibration conditions and trim P1 for the required change in output i e Trim the output for 0 5 47 5 8V SGA User Manual 06 05 07 SGAv2 5 13 61a 15 Chapter 5 Troubleshooting 1 No output Check power supply is present LED is on Check the output connections are correct Check terminations ensure insulation is not trapped in terminal cable break etc Check the senso
10. A User Manual 06 05 07 SGAv2 5 13 61a Cabling Power Connection Two power supply options are available SGA 220 230VAC 50 60Hz 110 120VAC 50 60Hz 5W Max 18 24V DC 5W approx 150mA fully loaded The SGA can be powered from AC or DC sources whichever is available It is also possible to connect BOTH AC and DC simultaneously for security of power supply Figure 2 2 Power Connection 220 230 V AC 110 120V AC 18 24 V DC L 9 L 9 p DOO ES S T L MA S gt J1P22000 Ja SGA INTERIOR TERMINALS N Q N LO J3 43 J1 B J2 eeeeee Standard mains 2 or 3 core cable PVC sheathed unshielded cable will suffice for the power NOTE Connect the appropriate power to the SGA For AC powering observe the correct transformer jumper connections as shown in Figure 2 2 above This diagram is also provided inside the lid Connections to the SGA input output signal and the power supply are made via 2 5mm field terminal connectors Cable entry in the cased versions is via glands in the ends of the case 4 SGA User Manual 06 05 07 SGAv2 5 13 61a Figure 2 3 Input Sensor Connections Strain Input Strain Gauge Output an Cable Shield J2 Excitation EUNT DA l oi od Strain Excite Excitation 10V 5V O SN l r t Shield oV I I pod Pm Q Ret 5V 2
11. E IE co En 18 co PIS 09 PIE mE 122 co VIN OS alnome VME Em i co co lo co gt al ES Pane lone P ne IP ev Olt exe INwe If we IP ed we ll wh e 4 ee Nwe we 2 co x GO x GO x GO x GO x o x o x o x GO x GO x GO x GO x GO x GO x GO x wo ILE EM BIO lo alone ome lo er ls alo lo e ne ZN Pen Pen gt SO 7 50 gt So gt Eo gt Eoc Eoc S a5 0 a5 0 aS 0c Soc S oc Eos recs Eo m EW PEW PEW EL Eme Eme Elo Ew IEW Eme Eme Ewe Eme Ewe En 9 ote pre yr Pete lore fete pre let let et mtm Br gt EY Soc Am RIN me Ome Eme Um co VIO mc Em gt S co mE Mm 5 lled m gt Eme nm gt 2 ak S ye S e So o Sue Fa gt Nao N Il e IF Qe la SI N olaa Na Ne SGA User Manual 06 05 07 SGAv2 5 13 61a 10 Example A strain gauge has a sensitivity of 2 809 mV V Select Switch Setting number 28 from Table 3 6 and fine tune with potentiometer Pl Table 3 7 sw1 6 0 yy DEDO IMA EEN F Refer to Chapter 4 for calibration details Shunt Calibration Switch SW1 8 SW1 8 connects a 120k 50ppm surface mount resistor across the Excitation and Input terminals of the SGA This shunts one arm of the connected load cell to produce a known change in output which can be used for calibration or checking the integrity of the load cell and associated wiring Table 3 8 2 3 4 5 6 7 8 iid atl al kel al E A y The 120k resistor can be taken out of circuit and replaced by a user d
12. LO ELO ELO ELO E LO IIE LO ELON ELO Se e LO A e LO a YE o tE lo Y o Y lo YE YE es gt lo YE o Y o Y AA YY AA 6 YE INFE es Am 5 Am gt Pm 4KK co Em BIN co gt mE OME 0 m eo FIM ME I coa ls me lam 1h me ls gt Qe G PIT ee ITN f e IPN IS NIT NEG Pac ITN ITN SIP GA gt Pa gt 4 HE llo gt DIE e la E Jae DIR DIS E i ER gt 18 PIS gt 18 gt gt GO x GO x GO x GO x GO x GO x GO x GO x GO x GO x GO x GO x GO x gt NE le E one one le e R e RIA E le hos aloe I KE oe PIER PIER RIE K gt SO So Eo SO gt So PIS 0 Eo Eo VIS 0 Eo I Oe S oc EOS EOS EOE 10 E10 PEW IEW PEW PEW PEWS En E t0 IEW Eme Ewe Eme Eme Eme iS ia sve lo Y o Y d a go T ot ol AN Alo Aa i ce tE ost 1109 S gt ME co DIM co Em 419 co e co gt E co gt ME IRM DING VIM RIM ME Nm 9 st me am S N lS N lS N Ile ue Sau ola IIS ie aso ie Ia sl ie IN N o a o Nao Na gt or A ln ele ne Jl gt Le DIR e li e llo DIB KH DISH DIS e Jl ee liio x 18 ME 18 x GO x GO x 00 x GO x GO x GO x GO x co x co x GO x co x co x GO x GO x co x gt NE rM Ere oye ne o e alo ea y NE y NE o ee one Ere eR PIER IE gt gt SO PISO O gt 50 50 50 PISO IS OF SO SO SO E OF EOS EOS EOS 10 Eo PEW En TE o En Eo gt Emc Eme Eme Eme Eme Ewe Eme Bio L E et gt lio Y e et lot gt o YE E e lot gt g Y AY gt o TE 4 es gt ODE IES CD
13. efined leaded component by carefully cutting the fine link as shown in Figure 3 3 Use the right hand pad and either of the left hand pads to fit the new component The surface mount resistor can be reinstated by re connecting the two pads either side of the cut link Figure 3 3 Shunt Cal link SW3 HIHIH e s Bo m SW1 Zero Offset Setting Switch SW2 This offset can be used to compensate for the transducer zero error to tare the scale dead load or to shift the output These settings allow the user to calibrate a zero offset The range allows for up to 79 of the span Potentiometer P2 provides fine adjustment SGA User Manual 06 05 07 SGAv2 5 13 61a 11 Table 3 9 sw2 1 2 3 4 5 6 7 8 Example An installation has a tare of 15 kg with a 200kg strain gauge that gives an output of 6 37mV V at 10V excitation The tare equates to 7 5 15 200 Set the switches to nearest 5 2 and fine trim with Potentiometer P2 The tare must be subtracted therefore the ve Offset switch SW2 2 should be ON The calibrated zero mV reading would be 4 78 mV i e 7 5 of 63 7mV Table 3 10 ea Note SW2 1 8 2 should never be ON together Either one or other should be ON if an offset is required otherwise both switches should be OFF Switch settings 3 to 8 are ADDITIVE The offset value of each switch is added to give a total offset of 7896 Fine adjustment is provided by potentiometer P2 12
14. ent de depends on loading 50 90 200 mA Bridge excitation 10V range Bridge excitation 5V range V See note 2 Bridge resistance 8 ms mV o i10 mw Offset adjustment Pot fine adj 25 por Offset adjustment Switchable coarse adj 1 25 79 YER Output load Voltage output Output load Current output l0 50 Bandwidth Nofilterand 2mvV DC f 6 iz Filtercutoff Switchable range 1 500 Hz Zero temperature coefficient 92 5mV V 0 002 0 009 Y 9C 2 5mV V FR Spantemperaturecoeffient 0007 oor e linearity 00 eR Gain stability 1st 1000 Hours 02 eR Gain stability 2nd 1000 Hours 01 eR L90 day Offset stability 33 jw Output load stability gain 0 10009 Joo r Output load stability offset 0 100 oor wR Power supply rejection gain 0 10009 oor wR Power supply rejection offset 0 100 oor wR Operating temperature range 10 50 e Storage temperature range 20 ofc Humidity Tf Note 1 18V max at full load Note 2 Switch SW4 8 on for 10V excitation off for 5V excitation Table 3 2 Output options 10V V 0 10V 0 5V 0 20mA 4 20mA Connections Field screw terminals 2 5mm rising clamp Enclosure ABS case 160 x 80 x 55 sealed to IP65 fitted with 3 off cable glands Control
15. expected a Check the installation for problems and repair where necessary b Poor termination C High resistance on cable leads d Low insulation impedance e Proximity to High Voltage Equipment Transformers Contactors Motors etc Noisy Environment a Check if the source can be found and remove noise b Check the cable shielding and ensure it is correctly installed and terminated 5 Calibration This section assumes that the unit is providing an output that is not stuck at top or bottom of the scale See paragraphs 1 to 4 if this isthe case Ensure you have the calibration set up correctly installed i e mV source and output as required Ensure you are connected to the correct sensor and not to another adjacent unit Ensure you have the correct calibration data from the sensor manufacturer This must include a certified table with offset zero and linearity Ensure the temperature and other environmental parameters are within specification and where necessary taken into account when calibrating should such parameters have an effect on the calibration 6 Fine Span Gain and Zero Offset Adjustment Problems If the adjustment cannot reach the maximum output desired then check the tare is not too high If the potentiometer does not alter the output the unit must be repaired remove from service It is always wise to check a known good SGA against the problem installation before rejecting the suspect SGA SGA User Manual 06
16. f 800Hz can be switched into the SGA input by fitting a link to J P3 see Figure 3 2 Important Low pass filtering is switched into operation by setting SW4 6 ON and SW4 7 OFF J Reverse these settings to bypass the filter It should be noted that either one of these switches MUST be on but not BOTH 8 SGA User Manual 06 05 07 SGAv2 5 13 61a Example The Switch Settings for a cut off frequency of 50 Hz setting is illustrated below Note SW4 6 must be ON and SW4 7 must be OFF Table 3 5 sw3 1 2 3 4 5 6 7 8 50Hz 1 1 1 1 1 1 1 1 S HABE aaa sy INN mma Output Current Mode and Input Filter Settings Jumpers JP1 JP2 amp J P3 Figure 3 2 Terminals and jumper positions Refer to Figure 2 4 for details of wiring connections to J 1 Terminals and Jumper Positions Current Output Options Source mode Sink mode 800Hz Input filter Filter out Filter in fl SI JP2 JP1 E Ga JP2 JP1 SGA User Manual 06 05 07 SGAv2 5 13 61a SW1 8 switches on the shunt cal function see Table 3 8 OFF 0 ON 1 4 Ranges 1 to 60 from 0 06 mV V to 30 30 mV V Span Gain Setting Switch SW1 co x GO x co x GO x co x co x co x GO x co x GO x GO x co x She one o Re lo e alone lo e o e lo alot one JER PIER PIER PIER gt SO So So S50 gt So Sxc So gt So So gt Soc So EOS EOS EOS EOS LO ELO ELO E
17. g the two jumpers J P1 and J P2 to the outside positions See Figure 3 2 In Source mode the ve end of the load is connected to the SGA output and the current is sourced by the SGA output through the load towards ground 0V This mode has the advantage that the negative output connection is common to the load cell Excitation terminal Select this option by fitting the two jumpers J P1 and J P2 to the inside positions See Figure 3 2 See Chapter 3 for switch settings and details of SINK amp SOURCE jumpers 6 SGA User Manual 06 05 07 SGAv2 5 13 61a Chapter 3 Switch Settings Switch Positions On offf e g The switches in Figure 3 1 are depicted as ALL ON Figure 3 1 Output Settings Switch 4 Analogue Output D Patito URRH Use switch 4 to select the required output and if aua required the low pass filter and 5V Excitation i po See Tables 3 1 and 3 2 cn CE d o Table 3 1 Output Option a ea ao al T T T T T T T T T PO a oma ima ima 5V 25V w V Ao po op yop y t i N B Full scale output on the voltage ranges is achieved with a bi polar input Note 1 Negative inputs can be accommodated on the current output ranges by setting the Zero switch SW2 to 45096 Table 3 8 and setting SW1 to twice the required mV V setting Table 3 6 Table 3 2 Switch 4 Analog Output and Excitation Voltage Options SW4 SWA 1 2 3 4 5 6 7 8 X 1T 10V Exc OL35V E
18. incerface ADVANCED FORCE MEASUREMENT USER MANUAL MODEL SGA STRAI N GAUGE TRANSDUCER AMPLI FI ER Interface Inc 7401 E Butherus Dr Scottsdale AZ 85260 USA 480 948 5555 FAX 480 948 1924 www interfaceforce com gen interfaceforce com SGA User Manual SGAv2 5 13 61 06 05 07 Contents Chapter 1 Introduction to SGA ss sss sees sees rees ees essen nn nann nua nau RRR RRR LUE AUG ER A E GE E Gu E n Hu n n n n n 2 Figure 1 1 SGA Signal Conditioner ec teet eee d Ripe rex Prater E Ede R E RA REA E a 2 Chapter 2 Installing the SGA ocooococcconcconccnncnancnncnnrannrannrnrananan a a GG HA AGGER AUGERE UU A RR E GR nR 3 Pre Instala reo LEE ERO b RR e i eM RR 3 Figure 2 1 DimensiOns s cep A E RE DER 3 A LEE 4 Power Connection oo weit A A A AA A IRL REMISE E M 4 Figure 2 2 Power Connection ie ee EL eee ee MM rel pb LEX RR n REPE TEE LI 4 Figure 2 3 Input Sensor Connections e cece cece nc mem em emen nnn een nnn 5 O tput Connections asns yes eo OR shoes t teer Rc er rp IET Rte Per pl RE REY EAE E CUTE DER EXE RUE L ERE ee HL fea ER ERE RR 6 Figure 2 4 Output Connections eene eC d Rc EE Oe Ens EA LEER DR EE o R ERE E EOL 6 Chapter 3 Switch Settings ocoococcoconccocconcacancancancanrancnnnancnnrarenrannannrnrrnranrancancanrnrannaanannrarenraneanaass 7 Figure 3 1 Output Settings Switch 4 etecon mme messe eee e shes e rehenes ne nn nnns 7 Output Filter Settings SwIECh diia d bib EHE RI a o pol 8 Output Curre
19. l cables parallel to power cables Cross such cables at right angles The ground connection conductor should have sufficient cross sectional area to ensure a low impedance path to attenuate RF interference SGA User Manual 06 05 07 SGAv2 5 13 61a Output Connections Two analog outputs are available from the SGA proportional DC current and DC voltage The ranges available are as follows Output Range DC voltage 10V NB Maximum Load on voltage ranges is 2mA 35V 0 10V 0 5V DC current 0 20mA NB Maximum impedance 500R 4 20mA The DC current support both sink and source modes of operation Two jumpers J P1 amp J P2 provide the means of selecting the desired mode Figure 2 4 Output Connections Connections Current Output Sink Current Output Source Voltage Output SGA 15V rail SGA 15V rail OJT T ase SGA Output Supply Stage Isource LOAD Current Sink DODO SGA Output Supply a Stage Current Source eo o Oo o 9 JT Supply p 1 1 1 M 1 1 1 1 Isource Current flow Current flow 1 y T In Sink mode the ve end of the load is connected to the internal 15V supply on the SGA and the ve end is connected to the SGA output The current through the load is sunk by the SGA towards ground 0V N B In this mode neither connection to the output load is electrically common to the load cell Select this option by fittin
20. ll Bridge A Wheatstone bridge configuration utilizing four active elements or strain gauges Full Range Output The algebraic difference between the minimum output and maximum output Gain Gain is otherwise identified as SPAN It relates to the proportional output to the sensor input Calibration of the SGA is determined by setting the Gain Span and Offset Zero The amount of amplification used in an electrical circuit Ground 1 The electrical neutral line having the same potential as the surrounding ground 2 The negative side of power supply 3 Reference point for an electrical system Input Impedance Linearity The closeness of a calibration curve to a specified straight line Linearity is expressed as the maximum deviation of any calibration point on a specified straight line during any one calibration cycle Load The electrical demand of a process expressed as power watts current amps or resistance ohms Load Impedance The impedance presented to the output terminals of a transducer by the associated external circuitry Load cell The load cell is one of a series of Strain Gauge sensors that the SGA input is designed to accept Torque Sensor Pressure amp temperature transducers Low Pass Filter The SGA Module has a low pass filter to remove unwanted signals on the output This can be set to suit the installation from DC to 5kHz SGA User Manual 06 05 07 SGAv2 5 13 61a Millivolt One thousandth of a volt
21. ly loaded The sensitivity settings can be used to maximize the output when the full range of the load cell is not being used Here are a couple of examples Example 1 A 2 5mVNN load cell provides 10V for an l00lb load However it is never loaded above 50lb The sensitivity setting can be set to 1 25 mV V Table 3 6 20 1 20mV V SW1 1101 000 Example 2 When a reduced output is required from a fully loaded transducer use a less sensitive switch setting For an 8 volt output from a fully loaded 2 5mV V load cell use the 3 19mV V setting i e 10 8x2 5 3 125mV V Table 3 6 31 1 20mV V SW1 0010 000 SGA User Manual 06 05 07 SGAv2 5 13 61a 13 The SGA can be calibrated with the transducer connected provided that two calibration points can be implemented e g by applying known weights or forces If this is not possible a stable mV source or load cell simulator can be used provided that the precise sensitivity mV V and full range output kg of the transducer is known In this case the Ref 5V 2 5V output should be connected to Strain Input and the mV source applied between Strain Input and Strain Input Actual calibration is carried out in the following way 1 Set the correct switch settings on SW1 as described above using the transducer s calibration sheet supplied by the manufacturer This is normally specified as sensitivity or full range output and should be in mV V Apply the known low calibratio
22. n conditions weight force or mV V this may be zero if required and note the analog output having ensured that the SW1 settings are correct for the transducer sensitivity as step 1 above Apply the known high calibration conditions for optimum accuracy this should be at least 75 of full load and note the analog output Use the fine trim control P1 to obtain the required change in Volts or mA between the two calibration points steps 2 and 3 e g If the required output at the low calibration point is OV and the required output at the high calibration point is 7 5V adjust P1 in step 4 to produce a change of 7 5V between the calibration points Initially the low calibration point may not produce OV at the output If this is the case note the reading e g 0 5V apply the high calibration conditions and trim P1 for the required change in output i e Trim the output for 0 5 7 5 8V Use the fine Zero control P2 in conjunction with the coarse switches SW2 3 8 and polarity switches SW2 1 and 2 to set the output to the required absolute values Each switch within SW2 offsets the output by a particular percentage of full scale as shown in Table 3 9 NOTE It may be necessary to repeat these steps until the required output is achieved SGA User Manual 06 05 07 SGAv2 5 13 61a 14 Figure 4 1 Calibration Connections using Millivolt Source J2 S Strain Excite Excitation 10V 5V Y Shield OV Ref
23. nt Mode and Input Filter Settings JumpersJP1 JP2 amp JP3 ssssssssse nn nnrnnnrs 9 Figure 3 2 Terminals and jumper posSItiONS oooooccccccccnccnnonconconnonncnnoncnn cnn me eese mese enne nnn 9 Span Gain Setting Switch Wa 10 Shunt Calibration Switch SWI1 8 icis etx ed ED ERE at 11 Figure 3 3 Shunt Cal links oic E CR en EE ORE REPRE ERE e EL See eins c d id 11 Zero Offset Setting SwitEh SW2 uiii e br tu dis peux Er text Et d ride FER RUE ER TE da RO eA LER ORE EE EEN 11 Chapter 4 Calibration vcs css aas crre ni Ea RS rC T TR nennen YT nana daa daa a n a na na d uu n n n n 13 SENS ptc How rrr TUE MR 13 Figure 4 1 Calibration Connections using Millivolt S0urCge eee K K K meme 15 Chapter 5 Troubleshooting coococcococcoocconcncancancancancanranrnncaninnrarcnranras aaa aaa nada ada a da a n aa nau na uu n na nn 16 Chapter 6 Product e sensus san na na aa AGB AN GN RN GUN GRAL GE GR RU GA GG A Gu Ru n un nu n n nn 18 Chapter 7 GloSSAry MMMMM E 19 Chapter 8 Specifications for SGA Load Cell Amplifiers s sss ess sse ess sse ess sse ress sse essen nennen nnn nnn 22 uem vgl TTT 23 Warrant EDEN 23 Figure 8 1 Connection DetallS oooooccoccccccccnccnncnnnnnnnnrnnrnnn ensem E ee e she nennen nnn nene 24 SGA User Manual 06 05 07 SGAv2 5 13 61a Chapter 1 Introduction to SGA The Strain Gauge Amplifier SGA The SGA is a Strain Ga
24. o Strain Input and of J 2 with the power off d Check the Excitation voltage J 2 is at 10V DC e Check the calibration Incorrect setting of the calibration Span switches is the most common cause of low output particularly when associated with X Voltage outputs Refer to the calibration instructions in Chapter 4 Refer to tutorial on the calibration set up f Check the Zero offset is correct for the sensor This too is a common reason for low outputs 3 High output This is when an output is present but higher in span or zero than required b Check the sensor is connected typically reading 350 Ohm across Strain Excite and and also Strain Input and of J 2 with the power off C Check the Excitation voltage J 2 is at 10V DC d Check the Zero offset is correct for the sensor This is a common reason for high outputs where the offset is either omitted or incorrect for the sensor Refer to the calibration instructions in Chapter 4 e Refer to tutorial on the calibration set up f Check the calibration Incorrect setting of the calibration span switches is the most common cause of high output particularly when associated with x Voltage outputs 16 SGA User Manual 06 05 07 SGAv2 5 13 61a 4 Unstable Output This is when the output is unstable or varies The cause could be a poor installation or b a noisy environment Poor Installation This is when an output is present but higher or lower in span or zero than
25. pter 7 Glossary The total noise floor from all sources of interference in a measurement system independent of the presence of a data signal See noise readings gauge The process of adjusting an instrument or compiling a deviation chart so that it s reading can be correlated to the actual value being measured CMR The ability of an instrument to eliminate the effect of AC or DC noise Common Mode between signal and ground Normally expressed in dB at dc to 60 Hz One Rejection type of CMR is specified between SIG LO and PWR GND In differential meters a second type of CMR is specified between SIG LO and ANA GND METER GND Common Mode Rejection The ability of an instrument to reject interference from a common voltage at its input terminals with relation to ground Usually expressed in db decibels Deadband hysteresis Hysteresis In a digital controller there may be one switching point at which the signal increases and another switching point at which the signal decreases The difference between the two switching points is Hysteresis A change of a reading or a set point value over long periods due to several factors including change in ambient temperature time and line voltage along with a DC supply for additional security normal operation Fine Adjustment The Zero and Span calibration have a Fine Adjustment to give accuracy to the calibration These are potentiometers P1 and P2 for span and zero respectively Fu
26. r is connected typically reading 350 Ohm across Strain Excite and and also Strain Input and of J 2 with the power off e Check the Excitation voltage J 2 is at 10V DC a b c d 1 a For voltage output a Check V out and V out terminals are wired b Check the load is connected and is not open or short circuited c Check SW4 settings are correct for Voltage Output see Chapter 3 Table 3 2 d Check Span and Zero settings SW1 and SW2 1 b For current output a Check Isink and Isink terminals are used for Sink current output b Check Isource and Isource terminals are used for Source current output c Check the load is connected and is not open circuit d Check load does not exceed 500 Ohms e In Sink mode check 15 V is present at ve terminal of load f In Source mode check the ve terminal of the load is connected to ground g In Sink mode check the load is isolated from the load cell sensor excitation h In Source mode check the ve output is common to the ve Excitation i Check output SW 4 settings are correct for current see Chapter 3 Table 3 2 j Check Span and Zero settings SW1 and SW2 see Chapter 3 Table 3 6 amp 3 9 2 Low Output This is when an output is present but not of sufficient magnitude to meet the required value b Check power supply is within specified limits i e is not low C Check the sensor is connected typically reading 350 Ohm across Strain Excite L and and als
27. s Gain pot Offset pot Coarse gain switches Coarse offset switches Filter cut off switches Output mode switch 22 SGA User Manual 06 05 07 SGAv2 5 13 61a EMC Approvals Emissions BS EN 55011 1998 Immunity BS EN 61000 4 2 1995 IEC 6100 4 2 1995 BS EN 61000 4 3 2002 BS EN 61000 4 4 2004 BS EN 61000 4 11 2004 Output shall not exceed the sum of uncertainties when subjected to an electric field of 10V m over the frequency range 80 to 600MHz Safety Low voltage Directive 73 23 EEC as amended by 93 68 EEC BS EN 61010 1 2001 IEC 61010 1 2001 Warranty Interface warrants that its instruments shall be free from defects in material and workmanship for one year under normal and proper use when correctly installed SGA User Manual 06 05 07 SGAv2 5 13 61a 23 Figure 8 1 Connection Details uoneyoxa mE e uoneyoxa 3nduj ules 0 Jay 39euuoo uoneJqi eo 104 e24nos Au e Buisn jl OJeZ YOOYO O 9 IU UIEAIS 01199uu0 y y uoneyoxe AG Buisn J Ag 2 AS 1e AjeurtuoN ueeJos o6neb ues 9 aayebau NSd 0 UOWWWOS q N xew suuo 00S _ jndjno juaJno apow NOS m ueeJos eDneD urens JO e neBeu NSd 0 uouuo9 jou g N xew suyo 00S _ indmo juaJino pow AUIS xew yuz nd no eBeyoA 4 S 199114 Indu 2H00 8 uowwog A uowwog apou asnos apou UIs n LI o o O jeu O 934 AOL AS ZMS 19SHO O18Z uaz zd yndu ures indu uies ASIAG C AQ uee os PO SOX
28. uge Amplifier converting a strain gauge input to a Voltage or current output otherwise known as a Signal conditioner The SGA provides a wide range of signal conditioning for Strain gauges Load cells Pressure and Torque transducers Figure 1 1 SGA Signal Conditioner Inputs Load Cells Strain Gauges Torque Transducers Pressure Transducers STRAIN GAUGE AMPLIFIER OUTPUT 10V 110 230 V AC 15V 18 24V DC 0 5V 0 20mA 4 20mA INPUT Transducer SENSITIVITY of between 0 1 mV V and 30 mV V are possible This is achieved by a combination of gain span DIP switches and associated fine adjustment by a potentiometer Similarly transducer zero OFFSET and SCALE DEAD BAND of up to 79 can be compensated for in the module This is achieved again by a combination of zero DIP switches and associated fine adjustment by a potentiometer The module has built in FILTERS to cancel the field effects of vibration agitation and electrically noisy environment The on board low pass filter can be switched in and adjusted from 1Hz to 5kHz using a series of DIP switches A wide range of proportional output options for currents and voltages can be configured by DIP switch settings The board is mounted in an IP65 NEMA 4X ABS case 2 SGA User Manual 06 05 07 SGAv2 5 13 61a Chapter 2 Installing the SGA Pre Installation See Specification details in Chapter 8 for details of Environmental Approvals Carefully remove the SGA unit from
29. xc 1T 10V Exc 01 5V Exc 1T Filter in 1TFilter out 11 Filter in 1TFilter out 020m X x x o 1T Filter in 1fFilter out 4 220mA X X X 41 1T ilter in 1TFilter out 11 210V Exc 0L 5V Exc Fiterout X X x x Fiterin X X x XxX 10VEx X x x x T Filter in 1 Filter out T Filter in 1fFilter out Switch settings 0 2Off 1 On X Don t Care Important Low pass filtering is switched into operation by setting SW4 6 ON and SW4 7 OFF Reverse these settings to bypass the filter It should be noted that either one of these switches MUST be on but not BOTH SGA User Manual 06 05 07 SGAv2 5 13 61a Example 0 10 Volt output with no filter required Table 3 3 sw4 1 2 3 4 5 6 7 00 0 10V 0 4 T y SWA K Output Filter Settings Switch 3 The SGA incorporates a second order 12dB oct low pass filter that can be switched in to improve the performance and output signal quality in electrically noisy environments It can also be used to reduce the effects of high frequency fluctuations in the load or applied force to the load cell The cut off frequency of the filter is set by the DIP switch SW3 as illustrated in the table below Table 3 4 Switch 3 M un D D 2 o S m i rz um m P Note A SECONDARY low pass filter with a cut off frequency o
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