Author: Noyafa–Cable Tester Manufacturer
Analysis of common faults of cable fault tester on site When the measuring device is normal, the common fault analysis of the cable fault tester on site Experience judgment (1) When the measuring device is normal, the integral error (including CT error, secondary wiring error and instrument error) is±3%. (2) When the comprehensive error is between -10% and -3%, it is usually possible a, meter is not allowed b, CT secondary load weight c, CT negative error (3) When the comprehensive error exceeds 10% , may be a, CT secondary wiring is wrong b, CT is wrong c, phase loss or wrong phase Usually, comprehensive error measurement can be carried out in field work. When the combined error is±At 3%, the system basically has no problems.
When the comprehensive error is large, CT error, meter error check and line diagnosis can be performed separately. 3. Common problems of cable fault tester (1) Lack of a phase When the phase voltage or current is missing, it can be“Measurement parameter 1”or“vector image”function to see directly. Phase loss is usually caused by a failure of one of the three components of the metering device or disconnected wiring.
The specific possible reasons are as follows: a. The voltage coil of the electric energy meter is not connected (the coil is broken, lightning strikes, the voltage hook and the screw are not in contact) b. The measuring circuit measures the fuse once or the contact is not good. c. The single-phase circuit of the voltage secondary circuit is open (fuse or poor contact) d. The single-phase current coil of the ammeter or the CT itself or the secondary winding of the CT is open (the coil is blown, and the terminals of the electric energy meter or the secondary terminals cannot be contacted) e, the secondary Phase current open circuit in the current loop (2) The cable fault tester can show that the field calibrator lacks two phases The causes and conditions are basically similar to the lack of one phase. (3) A current phase or several opposite directions from“vector”The function can see the current reversal.
For example, the situation shown in the figure above is that the A-phase current reverses, and the reverse angle exceeds the normal value of 180°. The reasons for this phenomenon are: a, A phase CT K1, K2 are reversed b, the phase CT cable is not in the direction c, K1, K2 on the CT do not match the actual label (4) The voltage and current are not the same as the phase voltage and current One phase or several phases do not correspond, so the actual angle is 120 from the normal°or 240°.
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