In power systems, circuit breaker position indicator lights are the most direct window for maintenance personnel to judge equipment status. When the "open" or "closed" status displayed by the indicator light is inconsistent with the actual mechanical position, it often indicates a hidden danger in the secondary circuit. Based on typical field fault cases, the causes mainly fall into the following three categories:
1.Reduced insulation in the control circuit
This is a common cause of "false indications." Moisture and aging insulation in outdoor terminal boxes can lead to a decrease in insulation resistance or even breakdown between the closing and tripping circuits. For example, in the closed state, the negative potential of the tripping circuit may enter the closing circuit through the insulation failure point, causing the trip position monitoring relay (TWJ) to malfunction, resulting in the strange phenomenon of "red light constantly on, green light flashing." This type of fault often appears intermittently, repeating with changes in ambient humidity.
2. Incorrect wiring and poor contact in the secondary circuit
Incorrect or loose wiring can disrupt the monitoring logic. If the closing position monitoring circuit core is incorrectly connected, the position relay may be in an abnormal state of being energized or de-energized for a long time, and the protection device will be unable to issue an alarm. In addition, loose wiring of the control power circuit breaker, poor contact of auxiliary switch contacts, or insufficient travel can also disrupt the integrity of the opening/closing circuit, resulting in an incorrect "control circuit disconnection" signal and abnormal indicator lights.
3. External AC power interference
In complex circuits, if the disconnector interlocking circuit and the circuit breaker control circuit share a cable, AC power may be induced into the DC control circuit. This interference voltage is sufficient to cause the position indicator light to illuminate abnormally, but insufficient to drive the circuit breaker to operate, easily leading to misjudgment.
Troubleshooting recommendations:
When encountering such faults, judgment should not be based solely on indicator lights. The actual condition should be confirmed by combining the circuit breaker's mechanical position indicator and electrical instrument readings. Subsequently, the control power supply voltage, the insulation condition of the outdoor terminal box, and whether the auxiliary switch contacts are properly switched should be carefully checked.
Shaanxi West Power Tongzhong Electrical Co., Ltd.
Our address
Nanpo Village, Chencang Avenue Jintai District Baoji City, Shaanxi Province, China.
Phone Number
+86 18091765882(WhatsApp/Wechat/facebook)
