Darui Electric recommends:
XJYB-3000 Handheld Zinc Oxide Arrester Live Analyzer Operation Modes
PT Mode
The instrument inputs the PT secondary voltage as the reference signal, and simultaneously inputs the MOA current signal. Through Fourier transform, the voltage fundamental wave U1, current fundamental wave peak Ix1p, and current-voltage angle Φ can be obtained. Therefore, the component in phase with the voltage is the resistive current fundamental wave peak (Ir1p), and the orthogonal component is the capacitive current fundamental wave peak (Ic1p): Ir1p=Ix1pCOSΦ Ic1p=Ix1pSINΦ
Considering that δ=90°—Φ is equivalent to the dielectric loss angle, directly using Φ to evaluate MOA is also very simple: when there is no "interphase interference", Φ is mostly between 81°~86°. According to the requirement that "the resistive current should not exceed 25% of the total current", Φ should not be less than 75.5°. Refer to the table below for segmented evaluation of MOA performance:
Performance
<75°
75°~77°
78°~80°
81°~83°
84°~89°
>89°
Φ
Poor
Bad
Fair
Good
Excellent
Interference
Actually, attention should be paid when Φ<80°.
Grounding:
Connect the ground wire before measurement, and disconnect the ground wire last after measurement! If there is paint or rust at the grounding point, it must be cleaned thoroughly.
Reference Voltage
Insert one end of the reference voltage signal line into the reference voltage socket, and connect the other end to the PT secondary low-voltage output of the phase under test: the small black clip connects to the neutral point (x), and the small red clip connects to phase B voltage). When using external application method, connect to the measuring winding of the step-up transformer. If the PT is far away, an extension line can be used.
Current Signal
First insert the leakage current signal line plug into the instrument, then clamp the other end clip (or use an insulating rod to attach) to the upper end of the discharge counter of the MOA under test. In the laboratory, the MOA without a discharge counter can be placed on an insulating board, and the current signal can be taken from the lower end of the MOA. Extension lines cannot be used for the current signal. The wiring diagram is as follows: (Figure 2)
Induction Mode (customized upon customer request):
An electric field induction sensor is set on the MOA base. Its induced current leads the electric field strength (bus voltage) by 90°. After integral operation, it is in phase with the electric field strength or bus voltage. Therefore, the signal from the electric field induction sensor can be used as the measurement reference. The instrument inputs the electric field induction sensor signal and simultaneously inputs the MOA current signal. Through Fourier transform, the electric field fundamental wave E1, current fundamental wave peak Ix1p, and current-electric field angle Φ can be obtained. The component in phase with the electric field is the resistive current fundamental wave peak (Ir1p), and the orthogonal component is the capacitive current fundamental wave peak (Ic1p).
Using B-phase induction signal as reference
Because the electric field influence of the A/C side phases on the B-phase base cancels out, the induction plate should be placed on the B-phase MOA base at a position symmetrical to the A/C phases to obtain correct phase information for the B phase. The electric field on the A/C phase MOA bases is affected by the B phase, so do not place the induction plate on the A/C phase MOA bases. The wiring diagram is as follows: (Figure 3)
3. No PT Mode:
Only the current line is needed. Once the current signal is obtained, the total current and resistive current can be measured.
Current Signal
First insert the leakage current signal line plug into the instrument, then clamp the other end clip (or use an insulating rod to attach) to the upper end of the discharge counter of the MOA under test. In the laboratory, the MOA without a discharge counter can be placed on an insulating board, and the current signal can be taken from the lower end of the MOA. Extension lines cannot be used for the current signal. The wiring diagram is as follows: (Figure 4)
Wireless:
The instrument uses the received wireless signal as the reference voltage, and simultaneously inputs the MOA current signal. Through Fourier transform, the voltage fundamental wave U1, current fundamental wave peak Ix1p, and current-voltage angle Φ can be obtained. Therefore, the component in phase with the voltage is the resistive current fundamental wave peak (Ir1p), and the orthogonal component is the capacitive current fundamental wave peak (Ic1p): Ir1p=Ix1pCOSΦ Ic1p=Ix1pSINΦ
Considering that δ=90°—Φ is equivalent to the dielectric loss angle, directly using Φ to evaluate MOA is also very simple: when there is no "interphase interference", Φ is mostly between 81°~86°. According to the requirement that "the resistive current should not exceed 25% of the total current", Φ should not be less than 75.5°. Refer to the table below for segmented evaluation of MOA performance:
Performance
<75°
75°~77°
78°~80°
81°~83°
84°~89°
>89°
Φ
Poor
Bad
Fair
Good
Excellent
Interference
Actually, attention should be paid when Φ<80°.
Grounding:
Connect the ground wire before measurement, and disconnect the ground wire last after measurement! If there is paint or rust at the grounding point, it must be cleaned thoroughly.
Note: The above information and technical parameters are compiled and released by Yangzhou Darui Electric Co., Ltd.
