- The COMPANO 100 test set can output life-hazardous voltages and currents.
- Before operating any such electrical equipment, carefully read the Safety Instructions chapter in this manual (see Safety instructions).
| WARNING | ||
| Death or severe injury can occur if the appropriate safety instructions are not observed.
|
This chapter provides you with examples how to perform basic tests on a voltage/potential transformer (VT/PT). VT/PT circuits in general have an MCB (Miniature Circuit Breaker) for overcurrent protection in the circuit. The MCB is open for all tests. Apart from that, it is not necessary to open any connections of the secondary wiring.
| WARNING | ||
| Death or severe injury can occur if the appropriate safety instructions are not observed.
|
Connect the V OUT output of the COMPANO 100 test set to the VT/PT’s primary contacts A/H1 and N/H2.
Connect the VT/PT’s secondary contacts a/X1 and n/X2 to the IN 1 input.
Turn off the output I OUT by first pressing the I OUT key, and then by pressing the "Off" soft key.
Voltage output V OUT is configured to be AC by default.
Configure IN 1 to be a voltage input by first pressing the IN 1 key, and then by pressing the following soft keys sequentially: Analog ► Voltage ► AC ► Auto ► fsel.
The frequency-selective measurement is needed because the expected voltage is very small. To avoid interferences with other signals, a frequency different from mains frequency, for example 80 Hz, is used. The frequency-selective measurement assures that only the 80 Hz components of the input signal are measured.
Configure the calculated measurement to measure a ratio. Press the Calculated measurement key, switch on the measurement, select V OUT as operand 1, IN 1 as operand 2, and Ratio:1 as calculated measurement.
Check the ratio of the VT/PT
Go to the QUICK application module.
Set a V OUT AC voltage of 150 V.
Set the output frequency to 80 Hz.
Start the output for say 2 seconds, and deactivate the output manually after that time.
The ratio is displayed as calculated result in the QUICK screen.
The phase angle of IN 1 should be around 0 °. If it is around 180 °, the VT/PT has a wrong polarity (which is, in fact, very unlikely).
| WARNING | ||
| Death or severe injury can occur if the appropriate safety instructions are not observed.
|
This chapter provides you with an example of how to measure the burden of a voltage/potential transformer (VT/PT).
Open the MCB (miniature circuit breaker) on the VT/PT’s secondary side.
Connect the COMPANO 100 test set’s output V OUT to the VT/PT’s secondary wiring behind the open MCB.
Attention:
Make sure you do not accidentally inject voltage to the secondary side of the VT/PT (to the VT/PT’s secondary contact a/X1, for example) as this would generate an unexpected high voltage on the primary side of the transformer.
Make sure the MCB is open.
Connect the COMPANO 100 test set’s input IN 1 to the same point, using a second set of connection wires.
Configure COMPANO 100's input IN 1 to be a voltage input: press the IN 1 key below the actual input. Press the following soft keys sequentially:
Analog ► Voltage ► AC ► Auto ► Accurate
Connect a current clamp to the COMPANO 100 input IN 2.
Note: perform a DC current offset calibration on the current clamp before carrying the measurement.
At the current clamp, set a range corresponding to the clamp type. The secondary current on VT/PT circuits is usually very low. In most cases the smallest range of the current clamp is suitable.
Apply the current clamp around a secondary wire of the CT.
Configure COMPANO 100's input IN 2 to be a current input. Press the IN 2 key below the actual input. Press the following soft keys sequentially:
Analog ► Clamp ► 100 mV/A* ► AC ► Auto ► Accurate
*Select the value corresponding to the current clamp. Use the jog dial wheel to set a value differing from the preset.
Turn off the output I OUT by first pressing the I OUT key, and then by pressing the "Off" soft key.
V OUT is configured to be AC by default.
In the QUICK application module at V OUT, set the nominal secondary voltage of your choice.
Press the Calculated measurement key 
. Then press the On soft key.
Configure the calculated measurement for apparent power by using the voltage at IN 1 as operand 1, and the input at IN 2 as operand 2.
Because one operand is a current and the other one a voltage, the Calculation setting provides an apparent power S option.
Now return to the QUICK application module, and inject the nominal secondary nominal voltage for 2 seconds. The measurement shows the secondary burden of the CT.
Open the MCB (miniature circuit breaker) on the VT/PT’s secondary side.
Connect the COMPANO 100 test set’s output V OUT to the VT/PT’s secondary wiring behind the open MCB.
Attention:
Make sure you do not accidentally inject voltage to the secondary side of the VT/PT (to the VT/PT’s secondary contact a/X1, for example) as this would generate an unexpected high voltage on the primary side of the transformer.
Make sure the MCB is open.
Turn off the output I OUT by first pressing the I OUT key, and then by pressing the "Off" soft key.
V OUT is configured to be AC by default.
Check the polarity of the VT/PT’s secondary wiring
Start the Polarity Check application module.