Shanghai Baixie Electric Technology Co., Ltd. independently researches and develops single-phase, three-phase zinc oxide arrester testers that use a unique high-speed magnetically isolated digital sensor to directly acquire input voltage and current signals, ensuring data reliability and safety. Resistive current fundamental peak output, side-phase correction and other functions.
Single-phase, three-phase zinc oxide arrester tester operation steps
1. Cable mode:
The instrument inputs the PT secondary voltage as the reference signal, and inputs the MOA current signal at the same time. After the Fourier transform, the voltage fundamental wave U1, the current fundamental wave peak value Ix1p and the current voltage angle Φ can be obtained. Therefore, the voltage in-phase component is the resistive current fundamental peak (Ir1p), and the quadrature component is the capacitive current fundamental peak (Ic1p):
Ir1p=Ix1pCOSΦ Ic1p=Ix1pSINΦ
Taking into account δ = 90 ° - Φ is equivalent to the dielectric loss angle, direct evaluation of MOA with Φ is also very simple: When there is no "inter-phase interference," Φ is mostly between 81 ° ~ 86 °. According to the requirement that the resistive current must not exceed 25% of the total current, Φ must not be less than 75.5°. Refer to the following table for a partial evaluation of MOA performance:
Performance <75° 75°~77° 78°~80° 81°~83° 84°~89° >89°
Good interference in Φ bad difference
Actually Φ < 80° should be noticed.
Grounding:
Connect the ground wire before measuring, and finally remove the ground wire after the measurement! If there is paint or rust on the ground, it must be removed.
Reference voltage
One end of the reference voltage signal line is inserted into the reference voltage socket, and the other end is connected to the secondary low-voltage output of the measured phase PT: the small black clip is connected to the neutral point (x), and the small red clip receives the phase detection voltage (a/b/c). The external measuring method is connected to the measuring winding of the step-up transformer. If the PT is far away, use an extension cord.
Current signal
The three-phase zinc oxide surge arrester charged tester inserts the plug of the leakage current signal wire into the instrument first, and then clamps the other end clamp (or catches it through the insulating crucible) to the upper end of the measured phase discharge MOA discharge counter. The MOA with no discharge counter can be placed on the insulation board in the test room, and the current signal is taken from the bottom of the MOA. The current signal cannot use extension lines.
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