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PROCEDURE MANUAL Issue Date: Issue No: Holder: 1.00 Company Name Issue No.9 Issued by Procedure Manual Date: Page 2 TABLE OF CONTENTS 1. SCOPE - AUTOMATIC GENERATION OF D.C. VOLTAGE FROM 100MV TO 1KV. ............................ 3 2. SCOPE - AUTOMATIC GENERATION OF 2 WIRE RESISTANCE FROM 10 TO 10M..................... 6 3. SCOPE - AUTOMATIC GENERATION OF 4 WIRE RESISTANCE FROM 0 TO 10K. ...................... 9 4. SCOPE - AUTOMATIC GENERATION OF D.C. CURRENT IN THE RANGE OF 0UA TO 2 AMPS. ... 12 5. SCOPE DC CURRENT SOURCE 2A TO 20A ................................................................................... 14 6. SCOPE - AUTOMATIC GENERATION OF A C VOLTAGE FROM 100MV, 40HZ TO L KHZ. ............. 16 7. SCOPE - AUTOMATED GENERATION OF AC CURRENT 0UA TO 2AMPS, 40HZ TO 1 KHZ ......... 18 8. 8.1. AC CURRENT SOURCE 2A TO 30A................................................................................................ 20 SCOPE - GENERATION OF AC CURRENT FROM 2A TO 30AMPS ....................................................................................... 20 9.1. RCD TIMER .................................................................................................................................... 22 SCOPE - RCD TIMER MEASUREMENT USING THE 2100/3200 .......................................................................................... 22 9. 10. INSULATION RESISTANCE ........................................................................................................... 25 10.1. SCOPE – INSULATION RESISTANCE METER CALIBRATION USING THE 2100/3200 ........................................................... 25 11. LOOP IMPEDANCE MEASUREMENT ............................................................................................. 27 11.1. SCOPE – LOOP IMPEDANCE MEASUREMENT USING THE 2100/3200 ............................................................................ 27 12. AC/DC CLAMP METERS ................................................................................................................. 30 12.1. SCOPE - CALIBRATION OF CLAMP METERS UP TO 1000A ............................................................................................. 30 ELECTRICAL PROCEDURE MANUAL V1.00 Company Name Issue No.9 Issued by Procedure Manual Date: Page 3 1. Scope - Automatic generation of D.C. Voltage from 100mV to 1kV. 1.1.1. Equipment 3000 Series Calibrator Precision Low thermal Lead set 1.1.2. Connection diagram 1.1.3. Measurement Method: 1) Allow all equipment sufficient time to stabilise, refer to manufactures handbook. 2) Check environmental conditions e.g. mains voltage/frequency, temperature are within laboratories limits 3) Use the low thermal lead set to connect the calibrator’s voltage output terminals to the input instrument under test. (See note 2) 4) Connect guard and earth as required. (See notes below) 5) Check the Zero of the measuring instrument and null if required. 6) Set the output voltage required from the instruments calibration procedure and turn output on. (For automated calibration ProCal will set the calibrator.) Refer to manufacture’s manual for equipment operation. ELECTRICAL PROCEDURE MANUAL V1.00 Company Name Issue No.9 Issued by 1.1.4. Procedure Manual Date: Page 4 Note 1: Safety Consideration The calibrator can generate hazardous voltages and great care must be taken to avoid the risk of shock. The use of shrouded leads, as supplied in the lead set is highly recommended. Note that any capacitance on the output will become charged to the output voltage, and if the calibrator is set to standby will be left charged presenting a shock hazard. Leads must not be connected or disconnected when high voltage is present 1.1.5. Note 1: Calibrator Trips back to standby The output of the calibrator is shorted or the resistance of the load is too low for the calibrator to drive. Note that for the 2000 series the factory set for the current limit is set to 10mA for safety reasons, this may be adjusted by internal trimmer up to 25mA if required. 1.1.6. Note 2:Errors due to thermal EMF voltages. Using the correct test leads is critical for low-level DCV measurements. The 2000 series calibrator’s terminals are gold plated copper and should be mated with the same type, avoid the use of nickel plated brass banana plugs. Thermoelectric voltages occur when different metals at different temperatures are connected together. This property is used in a thermocouple to measure temperature and 10’s of microvolts can easily be generated. To reduce thermal effects minimize the number of connection, use low thermal plugs made from gold and copper, and minimize temperature gradients and keep all equipment at the same temperature. 1.1.7. Note 3: Errors due to common mode voltages and pick up. It is recommend that the negative side of the calibrator’s output is earthed, an internal relay inside the calibrator can be selected for this, avoiding additional external connections. Letting the output float will allow both terminals to pick up common mode voltages with respect to earth which and may cause noise and unwanted errors in the measuring instrument. It is vet important however to only earth the signal at one place, see Note 3. If the measuring instrument has a guard terminal connect this to the low terminal for the optimum performance when the calibrator’s output is earthed. 1.1.8. Note 4: Errors due to earth & ground loops. To avoid errors introduced by earth loop’s only earth the output at one point. As there are often voltage drops in mains earth wiring, earthing at the calibrator output and at the measuring input will cause earth current to flow through the connecting lead (which is now in parallel with the mains earth) causing a voltage error. 1.1.9. Note 5: Errors due to Loading. All voltage sources have output resistance, to which the resistance of connecting leads etc must be added. Most modern measuring instruments are very high input impedance so the loading effects are negligible. Instruments with low input impedance such as thermal transfer standards will load the output and an allowance must be made. ELECTRICAL PROCEDURE MANUAL V1.00 Company Name Issue No.9 Issued by Procedure Manual Date: Page 5 1.1.10. Note 6: Special loading consideration on the 200mV range of the 2000 series calibrator The output impedance of the 200mV range on the 2000 series calibrators is 50 ohms. It is important to note this when calibrating moving coil type meters, which have low input impedance. Alternatively the 2Volt range can be used if the calibrator is being controlled by PC. 1.1.11. Note 7: Errors due Electromagnetic Interference (EMI) The leads connecting the instruments can pick up both magnet fields generated in all types of mains powered equipment from transformers, motors etc and RF interference from a mobile phone to a noisy switch mode power supply in a computer. Keep wire away from mains conductors and use screened cable to reduce noise on low level signals. 1.1.12. Uncertainties See spreadsheet ELECTRICAL PROCEDURE MANUAL V1.00 Company Name Issue No.9 Issued by Procedure Manual Date: Page 6 2. Scope - Automatic generation of 2 Wire Resistance from 10 to 10M. 2.1.1. Equipment 3000 Series Calibrator Precision Low thermal Lead set 2.1.2. Connection diagram 2.1.3. Measurement Method: 1) Allow all equipment sufficient time to stabilise as per manufactures handbook. 2) Check environmental conditions e.g. mains voltage/frequency, temperature are within laboratories limits 3) Use a high insulation screened lead to connect the calibrator’s resistance output terminals to the input-measuring instrument under test. (See diagram above) 4) Connect guard and earth as required. (See notes below) 5) Zero the measuring system by shorting the leads together at the calibrator. 6) Set the output required from the instruments calibration procedure and turn output on. (For automated calibration Procal will set the calibrator) Refer to manufacture manual for equipment operation. ELECTRICAL PROCEDURE MANUAL V1.00 Company Name Issue No.9 Issued by 2.1.4. Procedure Manual Date: Page 7 Important: Do not exceed the Maximum Power Rating Care should be taken that the applied voltages and current do not exceed the calibrator’s specification. Do not connect insulation testers or ductors which test at high currents, exceeding the maximum ratings will damage the resistor and change the resistance value. 2.1.5. Note 1: Errors due to leakage of test leads on high ohms To ensure accurate readings on high ohms (10megohms and above) use a cable with either Teflon, or polythene insulation. Do not use leads made from PVC or extra flex cable. A cable with 100Gohms insulation resistance will shunt the 1Gohm output by 1%, and the 100Mohm by 0.1%. The screen of the cable should almost always be connected to earth for minimum noise pick up. 2.1.6. Note 2: Errors due to contact and lead resistance on measurements below 1kohm When measuring resistance with a two-wire connection the resistance of the test leads and connection become very important below 1kohm. Although This resistance can be nulled out, (see note 5) this does not remove contact resistance variation, and in practice it is very difficult to use 2 wire measurements to accuracy better than a few milli-ohms. It is critical to make sure all connection are clean, and plugs & sockets are not worn or loose fitting. For accurate low ohm measurements 4-wire Kelvin type connection must be used. 2.1.7. Note 3: Nulling out lead errors Firstly short the end of the test leads together and ‘zero’ the DMM before connecting them to the calibrator to null out lead and connector resistance out. The 2000 series calibrators are calibrated for 2 wire ohms as the resistance seen at the terminals. 2.1.8. Note 4: Errors due to Earthing and Guarding. Earthing the resistance output can sometime introduce more noise on higher values in the reading as in some DMM’s the negative terminal in resistance mode is not the circuit low, but a current sink. Find the best connection by experimentally method. It may be best to connect earth to screen of the test leads and to the DMM’s guard, leaving the resistance measuring circuit to float. 2.1.9. Note 5: Errors due self-heating and voltage coefficients Measuring resistors at high power levels (above 0.5 watts) will cause the resistor to heat up, due to the temperature coeffient of the resistor the value will change. As the temperature rise reaches an equilibrium the value of resistance will also stabilise. When the power is removed the resistor will cool down and return to the original value. Generally the resistor should be measured at a power level, which will not cause self-heating, less than 10mW’s for example. Voltage coeffient is the change in resistance with voltage, high value film type resistor values will normally reduce at high voltages, and this effect is very small below 200Volts but may need to be considered above this. NOTE the resistors in the 2000 series maximum rating is 200V. ELECTRICAL PROCEDURE MANUAL V1.00 Company Name Issue No.9 Issued by 2.1.10. Procedure Manual Date: Page 8 Note 6: Errors due Electromagnetic Interference (EMI) The leads connecting the instruments can pick up both magnet fields generated in all types of mains powered equipment from transformers, motors etc and RF interference from a mobile phone to a noisy switch mode power supply in a computer. This produces great difficulties for high value (100Kohms) where impedance levels are high and test currents are low and every effort should be made to use screen leads which must be kept well away from sources of interference e.g. mains cables, computers, interface cables etc. Note to help reduce AC impedance the highest values of resistance in the 2000 series calibrator have a 100pF capacitance across. 2.1.11. Note 7: Measuring resistance with AC. Please note that this falls outside the scope of this procedure and has been included only for completeness Bridges often use AC to measure resistance, the resistors used in the 2000 series up to 100Kohms are of foil construction or non inductively wound and can be measured using AC up to 1kHz with little change in accuracy. 2.1.12. Uncertainties See Spreadsheet ELECTRICAL PROCEDURE MANUAL V1.00 Company Name Issue No.9 Issued by Procedure Manual Date: Page 9 3. Scope - Automatic generation of 4 Wire Resistance from 0 to 10k. 3.1.1. Equipment 3000 Series Calibrator Precision Low thermal Lead set 3.1.2. Connection diagram 3.1.3. Measurement Method: 1) 2) 3) 4) 5) Allow all equipment sufficient time to stabilise as per manufactures handbook. Check environmental conditions e.g. mains voltage/frequency, temperature are within laboratories limits Use a high insulation, low thermal screened lead and connect both the voltage sense leads, (to the top terminals) and the current drive leads the calibrator’s output to the measuring systems input. (see diagram above) Connect guard and earth as required. (See notes below) Select the zero ohms output from the calibrator and zero the measurement system ELECTRICAL PROCEDURE MANUAL V1.00 Company Name Issue No.9 Issued by 6) Procedure Manual Date: Page 10 Set the output resistance required from the instruments calibration procedure. Turn output on. (For automated calibration Procal will set the calibrator.) Refer to manufacture manual for equipment operation. 3.1.4. Important: Do not exceed the Maximum Power Rating Care should be taken that the applied voltages and current do not exceed the calibrator’s specification. Do not connect insulation testers or ductors which test at high currents, exceeding the maximum ratings this will damage the resistor and change the resistance value. 3.1.5. Note 1: Errors due to thermals on low ohms. Most resistance measuring instruments pass a DC current through the resistor and measure the voltage drop across it. For low values below 100 ohms and at low currents (10mA) often used by modern Digital multi meters makes the voltage to measure typically 100mV for 10ohms. A thermal generated EMF of 10uV in the test leads will give an error of 50ppM. Many high performance DMM’s have an ohms compensation function to automatically null this out. This should be used to improve the reading. If such a function is not available great care should be taken to use low thermal test leads. 3.1.6. Note5: Nulling out measurement systems zero Connect up sense and current wire to the calibrator, select zero ohms output on the calibrator and null the measurement system. The 3000 series calibrators are calibrated for 4 wire ohms as the resistance relative to the zero position 3.1.7. Note 6: Errors due to Earthing and Guarding. Earthing the resistance output can sometime introduce more noise on higher values in the reading as in some DMM’s the negative terminal in resistance mode is not the circuit low, but a current sink. Find the best connection by experimentally method. It may be best to connect earth to screen of the test leads and to the DMM’s guard, leaving the resistance measuring circuit to float. The 3000 series calibrators can internally earth the low side of the output. The condition of this is shown on the display and by a green front panel LED. 3.1.8. Note 7: Errors due self heating and voltage coefficients Measuring resistors at high power levels (above 0.5 watts) will cause the resistor to heat up, due to the temperature coefficient of the resistor the value will change. As the temperature rise reaches an equilibrium the value of resistance will also stabilise. When the power is removed the resistor will cool down and return to the original value. Generally the resistor should be measured at a power level, which will not cause selfheating, less than 10mW’s for example. Voltage coefficient is the change in resistance with voltage, high value film type resistor values will normally reduce at high voltages - this effect is very small below 200Volts but may need to be considered above this. NOTE the resistors in the 3000 series maximum rating is 200V. ELECTRICAL PROCEDURE MANUAL V1.00 Company Name Issue No.9 Issued by 3.1.9. Procedure Manual Date: Page 11 Note 8: Errors due Electromagnetic Interference (EMI) The leads connecting the instruments can pick up both magnet fields generated in all types of mains powered equipment from transformers, motors etc and RF interference from a mobile phone to a noisy switch mode power supply in a computer. This produces great difficulties for high value (100Kohms) where impedance levels are high and test currents are low and every effort should be made to use screen leads which must be kept well away from sources of interference e.g. mains leads, computers, interface leads etc. Note to help reduce AC impedance the highest values of resistance in the 3000 series calibrator have a 100pF capacitance across. 3.1.10. Note 9: Measuring resistance with AC. Please note that this falls outside the scope of this procedure and has been included only for completeness Bridges often use AC to measure resistance, the resistors used in the 3000 series up to 100Kohms are of foil construction or non inductively wound and can be measured using AC up to 1kHz with little change in accuracy. 3.1.11. Uncertainties See Spreadsheet ELECTRICAL PROCEDURE MANUAL V1.00 Company Name Issue No.9 Issued by Procedure Manual Date: Page 12 4. Scope - Automatic generation of D.C. current in the range of 0uA to 2 Amps. 4.1.1. Equipment 3000 Series Calibrator Precision Low thermal Lead set 4.1.2. Connection diagram 4.1.3. Measurement Method: 1) Allow all equipment sufficient time to stabilise as per manufactures handbook. 2) Check environmental conditions e.g. mains voltage/frequency, temperature are within laboratories limits 3) Use a 1 metre high insulation screened lead to connect the calibrator’s current output terminals to the inputmeasuring instrument under test. (See diagram above) 4) Connect guard and earth as required. (See note 1 below) 5) Check the Zero the measuring instrument and null if required. 6) Set the output current required from the instruments calibration procedure and turn output on (for automated calibration Procal will set the calibrator.) 7) Refer to manufacture manual for equipment operation. ELECTRICAL PROCEDURE MANUAL V1.00 Company Name Issue No.9 Issued by Procedure Manual Date: Page 13 4.1.4. Caution 1: When using currents above 1 amp take care to ensure the measuring instrument is on the correct range and the correct input is being used. 4.1.5. Note 1: Calibrators Compliance (or burden) voltage exceeded If the calibrator trips back into standby the calibrator’s output may be open circuit or the resistance to high to drive the set current. 4.1.6. Note 2: Errors due pick up and EMI interference when calibrating below 1mA Accurate measurement of Currents below 100uA can easily become swamped out by stray magnetic fields & pick up. Unlike DC voltage where impedances are very low a current source has very high output impedance, which is therefore more susceptible to induced noise, making the use of screened leads essential for accurate measurements. Guards should be connected to earth and also the low side of the output. ELECTRICAL PROCEDURE MANUAL V1.00 Company Name Issue No.9 Issued by Procedure Manual Date: Page 14 5. Scope DC Current Source 2A to 20A 5.1.1. Equipment 3000 Series Calibrator Precision Low thermal Lead set 5.1.2. Connection diagram 5.1.3. Measurement Method: 1) Allow all equipment sufficient time to stabilise as per manufactures handbook. 2) Check environmental conditions e.g. mains voltage/frequency, temperature are within laboratories limits 3) Use 20 Amp test leads to connect from the calibrator to the 20 Amp input terminals of the measuring instrument under test. Note high currents can melt low current test leads. (See diagram above) 4) Check the Zero of the measuring instrument and null if required. 5) Set the output current required from the instruments calibration procedure. Turn output on. (For automated calibration Procal will set the calibrator.) Refer to manufacture manual for equipment operation. 5.1.4. Caution 1: When using High currents take care to ensure the measuring instrument is on the correct range and the correct input is being used. 5.1.5. Caution 2: Inductive loads, coils etc can cause large back EMF voltages if suddenly disconnected, causing arcing which can damage instruments, always turn of output first before disconnecting. ELECTRICAL PROCEDURE MANUAL V1.00 Company Name Issue No.9 Issued by Procedure Manual Date: Page 15 5.1.6. Note 1: Calibrators Compliance (or burden) voltage exceeded If the calibrator trips back into standby the calibrator’s output may be open circuit or the resistance to high to drive the set current. 5.1.7. Note 2: Errors Due to self-heating. The accuracy of high Currents measurements are effected by self-heating increasing the temperature of the current shunts used to measure the current. This increase in temperature will change the value of the resistor, and hence the reading, In examples where this effect is very significant it may be necessary to record the time between the current first being applied and the measurement taken, or the temperature of the shunt. 5.1.8. Uncertainties See Spreadsheet ELECTRICAL PROCEDURE MANUAL V1.00 Company Name Issue No.9 Issued by Procedure Manual Date: Page 16 6. Scope - Automatic generation of A C voltage from 100mV, 40Hz to l kHz. 6.1.1. Equipment 3000 Series Calibrator Precision Low thermal Lead set 6.1.2. Connection diagram 6.1.3. Measurement Method: 1) Allow all equipment sufficient time to stabilise as per manufactures handbook. 2) Check environmental conditions e.g. mains voltage/frequency, temperature are within laboratories limits 3) Use a 1metre screened lead set to connect the calibrator’s voltage output terminals to the input instrument under test. (See diagram above) 4) Connect guard and earth as required. (See notes below) 5) Set the output voltage & frequency required from the instruments calibration procedure. Turn output on. (For automated calibration Procal will set the calibrator.) Refer to manufacture manual for equipment operation. 6.1.4. Note 1: Safety Consideration The calibrator can generate hazardous voltages and great care must be taken to avoid the risk of shock. The use of shrouded leads, as supplied in the lead set is highly recommended. ELECTRICAL PROCEDURE MANUAL V1.00 Company Name Issue No.9 Issued by Procedure Manual Date: Page 17 6.1.5. Note 1: Errors due to common mode voltages and pick up. It is recommend that the negative side of the calibrator’s output is earthed, an internal relay inside the calibrator can be selected for this, avoiding additional external connections. Letting the output float will allow both terminals to pick up common mode voltages with respect to earth which and may cause noise and unwanted errors in the measuring instrument. It is vet important however to only earth the signal at one place, see Note 3. If the measuring instrument has a guard terminal connect this to the low terminal for the optimum performance when the calibrator’s output is earthed. 6.1.6. Note 2: Errors due to earth & ground loops. To avoid errors introduced by earth loop’s only earth the output at one point. As there are often voltage drops in mains earth wiring, earthing at the calibrator output and at the measuring input will cause earth current to flow through the connecting lead (which is now in parallel with the mains earth) causing a voltage error. 6.1.7. Note 3: Errors due to Loading. All voltage sources have output resistance, to which the resistance of connecting leads etc must be added. Most modern measuring instruments are very high input impedance so the loading effects are negligible. Instruments with low input impedance such as thermal transfer standards will load the output and an allowance must be made. Capacitance of cables will also cause loading effects. 6.1.8. Note 4: Errors due Electromagnetic Interference (EMI) The leads connecting the instruments can pick up both magnet fields generated in all types of mains powered equipment from transformers, motors etc and RF interference from a mobile phone to a noisy switch mode power supply in a computer. Keep test leads away from mains conductors and use screened cable to reduce noise on low level signals 6.1.9. Uncertainties See Spreadsheet ELECTRICAL PROCEDURE MANUAL V1.00 Company Name Issue No.9 Issued by Procedure Manual Date: Page 18 7. Scope - Automated generation of AC current 0uA to 2Amps, 40Hz to 1 kHz 7.1.1. Equipment 3000 Series Calibrator Precision Low thermal Lead set 7.1.2. Connection diagram 7.1.3. Measurement Method: 1) Allow all equipment sufficient time to stabilise as per manufactures handbook. 2) Check environmental conditions e.g. mains voltage/frequency, temperature are within laboratories limits 3) Use a 1 metre, high insulation screened lead to connect the calibrator’s resistance output terminals to the input-measuring instrument under test. (See diagram above) 4) Connect guard and earth as required. (See note below) 5) Set the output current & frequency required from the instruments calibration procedure and turn output on. (For automated calibration Procal will set the calibrator.) Refer to manufacture manual for equipment operation. ELECTRICAL PROCEDURE MANUAL V1.00 Company Name Issue No.9 Issued by 7.1.4. Procedure Manual Date: Page 19 Caution: When using currents above 1 amp take care to ensure the measuring instrument is on the correct range and the correct input is being used. 7.1.5. Note 1: Calibrators Compliance (or burden) voltage exceeded. If the calibrator trips back into standby the calibrator’s output may be open circuit or the impedance is to high to drive the set current. Note the impedance (AC resistance) of inductive loads, such as coils, increases with frequency, which may limit the maximum frequency that can be used without exceeding the compliance voltage. 7.1.6. Note 2: Errors due to AC current leakage when calibrating below 1mA When connecting to other AC mains powered it is critical to use correct guarding is used. Currents can flow through the capacitive coupling to earth via the mains transformer inside the instrument instead of through the measuring circuit. The output from2000 series calibrator is sensed as the current flowing out of the positive terminal, this allowing the negative terminal of the calibrator and the measuring instrument guard to simple be earthed. To stop current from the positive terminal escaping down to earth before passing through the instruments measuring circuitry all capacitive route to earth should be removed, the most common route is to the screen of the connecting cable which if the cable is short the capacitance will be small and the effect negligible. Alternatively the screen could be driven with an active guard, which is beyond the scope of this procedure. ELECTRICAL PROCEDURE MANUAL V1.00 Company Name Issue No.9 Issued by Procedure Manual Date: Page 20 8. AC Current Source 2A to 30A 8.1. Scope - Generation of AC Current from 2A to 30Amps 8.1.1. Equipment 3000 Series Calibrator Precision Low thermal Lead set 8.1.2. Connection diagram 8.1.3. Measurement Method: 1) Allow all equipment sufficient time to stabilise as per manufactures handbook. 2) Check environmental conditions e.g. mains voltage/frequency, temperature are within laboratories limits 3) Use 30 Amp test leads to connect from the calibrator to the 30 Amp input terminals of the measuring instrument under test. Note high currents can melt low current test leads. (See diagram above) 4) Set the output current required from the instruments calibration procedure. Turn output on. (For automated calibration Procal will set the calibrator.) Refer to manufacture manual for equipment operation. ELECTRICAL PROCEDURE MANUAL V1.00 Company Name Issue No.9 Issued by 8.1.4. Procedure Manual Date: Page 21 Caution 1: When using High currents take care to ensure the measuring instrument is on the correct range and the correct input is being used. 8.1.5. Caution 2: Inductive loads, coils etc can cause large back EMF voltages if suddenly disconnected, causing arcing which can damage instruments, always turn of output first before disconnecting. 8.1.6. Note 1: Calibrators Compliance (or burden) voltage exceeded. If the calibrator trips back into standby the calibrator’s output may be open circuit or the impedance is to high to drive the set current. Note the impedance (AC resistance) of inductive loads, such as coils, increases with frequency, which may limit the maximum frequency that can be used without exceeding the compliance voltage. 8.1.7. Note 2: Thermal Shut down The calibrators power amplifier becomes overheated an internal sensor shuts the output off. (STBY !! is displayed). The user must wait for the amplifier to cool down again before the output can be turned on. 8.1.8. Note 3: Errors Due to self-heating. The accuracy of high Currents measurements are effected by self-heating increasing the temperature of the current shunts used to measure the current. This increase in temperature will change the value of the resistor, and hence the reading, In examples where this effect is very significant it may be necessary to record the time between the current first being applied and the measurement taken, or the temperature of the shunt. 8.1.9. Uncertainties See Spreadsheet ELECTRICAL PROCEDURE MANUAL V1.00 Company Name Issue No.9 Issued by Procedure Manual Date: Page 22 9. RCD Timer 9.1. Scope - RCD Timer measurement using the 2100/3200 This procedure covers the automatic testing of any digital loop tester and any electrical combination tester, which includes a RCD tester function. The 2100 is capable of testing RCD tester functions: RCD test current from 3mA to 3A: RCD trip times from 20ms to 5s:Current multipliers, I, 2I, 5I, ½ I 9.1.1. Equipment Transmille 2100 16th Edition Calibrator Calibrated adaptor lead 9.1.2. Connection diagram 9.1.3. Measurement Method 1) Allow all equipment sufficient time to stabilize as per manufactures handbook. 2) Check environmental conditions e.g. mains voltage/frequency, temperature are within laboratories limits 3) It should be firstly checked to see if the RCD tester which is going to be calibrated, is designated for use on a particular level of mains supply. This should be evident on the rating plate of the unit to be tested. A variac should have the 2100 plugged into it’s output and the voltage set to the corresponding value on the rating plate. (220V, ELECTRICAL PROCEDURE MANUAL V1.00 Company Name Issue No.9 Issued by ELECTRICAL PROCEDURE MANUAL V1.00 Procedure Manual Date: Page 23 Company Name Issue No.9 Issued by 4) Procedure Manual Date: Page 24 230V, 235.5V or 240V). Most modern RCD testers are immune to voltage changes. The older one’s are not. Therefore it is advisable to always have a variac supplying the 2100 regardless of age. 5) Connect the RCD tester to the 2100 IEC socket with the calibrated adaptor lead 6) Set the test current required on the 2100 and the tester from the instruments calibration procedure and press the test button on the RCD tester, (For automated calibration Procal will set the calibrator.) 7) Refer to manufacture’s manual for equipment operation. 9.1.4. Caution Live mains voltage is present on the 2100 output during this test. Care should be taken to avoid risk of electric shock. Note 1: 2100 Mains Supply The 2100 must be connected to an unprotected supply for this test as current is passed from live to earth, which will trip any RCD, protected supply. Note 2: 2100 displays warning message The tester may have a fault where excessive current is flowing in the earth conductor. ELECTRICAL PROCEDURE MANUAL V1.00 Company Name Issue No.9 Issued by 10. Procedure Manual Date: Page 25 Insulation Resistance 10.1. Scope – Insulation Resistance meter calibration using the 2100/3200 This procedure covers the measurement of high value resistance of any analogue or digital insulation testers and any electrical combination tester, which includes an insulation tester function. The 2100 is capable of testing insulation tester resistance functions: Resistance up to 1000V in the range 0.01MΩ to 10GΩ 10.1.1. Equipment Transmille 2100 16th Edition Calibrator set of silicon test leads. 10.1.2. Connection diagram 10.1.3. Measurement Method 1) Allow all equipment sufficient time to stabilize as per manufactures handbook. 2) Check environmental conditions e.g. mains voltage/frequency, temperature are within laboratories limits ELECTRICAL PROCEDURE MANUAL V1.00 Company Name Issue No.9 Issued by Procedure Manual Date: Page 26 3) Connect the insulation tester to the 4mm sockets at the bottom left of the calibrator using the set of silicon test leads, or the leads supplied with the instrument. 4) Select the correct procedure from the file for a manual calibration or from the Procal list for automated calibration. (This is normally an automatic function of Procal software when the instrument has been calibrated before). 5) Verify the procedure is the correct one and that the customer has not asked for any special requirements. All calibration within the Laboratory will be carried out using a procedure, which has been written and verified before use. 6) Following the procedure set the function and resistance required on the 2100, and press the test button on the tester, (For automated calibration Procal will set the calibrator.) Note - check battery voltage on tester. 7) Refer to manufacturers manual for equipment operation. 10.1.4. Uncertainties See spreadsheets. When using Procal the uncertainties are calculated as the test is performed, the calibration engineer entering the noise & flicker data together with the measurement. 10.1.5. Caution : Insulation testers produce high voltages, care should be taken to avoid shock. Note 1: Test Leads Test leads are important in the case of insulation testers. Good quality, high insulation resistance leads need to be used when testing to avoid leakage paths (to benches and the other test lead being used, which could have a shunting effect on the higher value resistance calibration) Note 2: Stability of readings Calibration at resistance values above 10MΩ requires care. As well as observing the requirements for test leads above, ‘Bodily’ movement, near to the test leads and calibrator, need to be avoided, to prevent inducement of static voltages being coupled into the test leads. Note 3: Test Leads Test leads are an integral part of loop tester calibration. As described above, only the extension IEC/13 socket lead calibrated with the 2100 may be used. Generally, instruments returned for calibration will have their own dedicated test lead supplied. This must be used and on booking in the instrument for calibration, an ID Number will have been placed on the lead linking it to the UUT. On the certificate, reference should e made stating, that the UUT was calibrated with the test lead (s) supplied. If no lead is supplied, then the laboratory reference leads should be used. These are standard leads for a variety of loop testers, which are calibrated. Reference to the Laboratory leads having been used, should be refereed to on the certificate front page. Note 4: Mains pickup Test leads and the UUT should be kept away from stray electrical fields (mains leads carrying mains voltages near to the test set up, can again cause coupling of noise into the test system) ELECTRICAL PROCEDURE MANUAL V1.00 Company Name Issue No.9 Issued by 11. Procedure Manual Date: Page 27 Loop Impedance Measurement 11.1. Scope – Loop Impedance Measurement using the 2100/3200 This procedure covers the automatic testing of any analogue or digital loop tester and any electrical combination tester, which includes a loop tester function. The 2100/3200 is capable of testing loop tester functions: Resistance in the range 0.05Ω to 1kΩ (lowest value dependant on the local supply loop impedance) 11.1.1. Equipment Transmille 2100 16th Edition Calibrator 11.1.2. Calibrated adaptor lead Connection diagram ELECTRICAL PROCEDURE MANUAL V1.00 Company Name Issue No.9 Issued by 11.1.3. Procedure Manual Date: Page 28 Measurement Method 1) Allow all equipment sufficient time to stabilize as per manufactures handbook. 2) Check environmental conditions e.g. mains voltage/frequency, temperature are within laboratories limits 3) Refer to the calibrator’s user manual for operating instructions. 4) Connect the Loop tester to the 2100 IEC socket with the calibrated adaptor lead. 5) The residual loop impedance of the source, up to the IEC socket first needs to be determined, whether the 2100 is being used manually or under computer control. Select the loop function on the calibrator’s menu and then press the ‘Auto Loop’ function. This will take about 30 seconds to determine the loop. This must be carried out if the calibrator is plugged into an alternative supply or at the beginning of any new loop test sequence. 6) Select the correct procedure from the file for a manual calibration or from the Procal list for automated calibration. (This is normally an automatic function of Procal software when the instrument has been calibrated before). 7) Verify the procedure is the correct one and that the customer has not asked for any special requirements. All calibration within the Laboratory will be carried out using a procedure, which has been written and verified before use. 8) Following the Procedure Set the loop resistance required on the 2100, and press the test button on the Loop tester, (For automated calibration Procal will set the calibrator.) 11.1.4. Uncertainties See spreadsheets. When using Procal the uncertainties are calculated as the test is performed, the calibration engineer entering the noise & flicker data together with the measurement. 11.1.5. Caution Live mains voltage is present on the 2100/3200 output during this test. Care should be taken to avoid risk of electric shock. Note 1: 2100/3200 Mains Supply The 2100/3200 must be connected to an unprotected supply for this test as current is passed from live to earth, which will trip any RCD, protected supply. Note 2: 2100/3200 displays warning message The tester may have a fault where excessive current is flowing in the earth conductor. ELECTRICAL PROCEDURE MANUAL V1.00 Company Name Issue No.9 Issued by Procedure Manual Date: Page 29 Note 3: Test Leads Test leads are an integral part of loop tester calibration. As described above, only the extension IEC/13 socket lead calibrated with the 2100 may be used. Generally, instruments returned for calibration will have their own dedicated test lead supplied. This must be used and on booking in the instrument for calibration, a number will have been placed on the lead linking it to the UUT. On the certificate, reference should be made stating, that the UUT was calibrated with the test lead (s) supplied. If no lead is supplied, then the laboratory reference leads should be used. These are standard leads for a variety of loop testers, which are calibrated. Reference to the Laboratory leads having been used, should be refereed to on the certificate front page. Note 4: Cleanliness of connections Dirty mains plugs, as well as worn mains plugs, can lead to significant errors at the lower loop value tests. The mains plug should be inserted and removed from adaptor lead several times to ensure oxidization has not built up on either the test lead with the UUT or adaptor lead. Note 5: Mains voltage noise / variations. Loop testers which have a 15mA loop test, make the measurement, sampled about 30 times, over the cause of about 30 seconds. In this time, mains borne noise and voltage variations are going to occur, even on the best of installations. Noise can happen, just with a soldering iron switching on its heater! If a totally incorrect reading is recorded or the noise flag comes up on the UUT, the test should be carried out again. ELECTRICAL PROCEDURE MANUAL V1.00 Company Name Issue No.9 Issued by 12. Procedure Manual Date: Page 30 AC/DC Clamp meters 12.1. Scope - Calibration of clamp meters up to 1000A 12.1.1. Equipment Transmille 3010 Transmille 1/5/50 Clamp Coil Adaptor 12.1.2. Connections 12.1.3. Measurement Method 1) Check that the mating faces of the jaws are both clean and alignment is correct. 2) Connect equipment as shown in diagram above. 3) Zero the clamp meter 4) Center the clamp meter jaws in the coil using the alignment table for the coil. (the position of the jaws in the coil affect the magnetic coupling, which causes variations on the UUT.) Some clamp meters may have an alignment mark, which should be oriented appropriately. 5) Apply the current and note the reading on the UUT 12.1.4. Uncertainties Individual uncertainty budgets will be created for each specific model of clamp meter allowing for repeatability due to the position of the clamp relative to the coil. Typical uncertainty calculations will contain 1) Imported uncertainty 0.04% @ 10A D.C.: Time Electronics 9823 2) Inter-reaction 0.24% + 0.04A : Manufacturers data for wound clamps 3) Repeatability - typically 0.5A : to be measured for specific models The above uncertainties will be combined using the method as detailed in M3003. ELECTRICAL PROCEDURE MANUAL V1.00