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Principle of Short Circuit and Ground Fault Judgment of Fault Indicator

Views: 154     Author: Site Editor     Publish Time: 2021-06-01      Origin: Site

1. Design Principle

The short circuit and earth fault indicator consists of the following parts: Three electrical short circuit fault sensors, one ground fault sensor, and one reading meter. The connecting wire is a cable and/or optical cable. The reading meter is housed in a plastic box, and the reading meter is equipped with a time reset circuit and assignment. The circuit ground fault is indicated by a flashing LED light, and the short-circuit fault on each cable is indicated by a flashing LED light. The reading meter is equipped with a test reset button. Each sensor is composed of a plastic shell and a coil that detects cable short circuit and ground faults causing pulse current. According to different versions of the sensor, the connecting wire is either fixed on the sensor, or the sensor is plugged in by the optical fiber. The shell is injection molded and meets the IP conditions. The optical fiber can safely transmit data through the high-voltage zone between the sensor and the reading instrument. The effective length of this optical fiber is up to 10 meters.

fault indicator



2. Principle of short circuit and ground fault judgment of fault indicator

There are many different types of power line fault indicators on the market.


1). Fault indicator using over-current principle

When a power short circuit or ground fault occurs in the line, the fault current in the line will increase. When the current increases beyond a certain set value, the line fault indicator using the overcurrent principle will give an alarm. Such indicators need to pre-set a power line short circuit and ground fault alarm threshold. The short circuit is generally 400A-1200A, and the grounding is generally 5-60A, and the range is adjustable. Currently, indicators using this principle occupy the mainstream market position.


2). Fault indicator using the principle of current mutation

When an electric wire short circuit or a ground fault occurs in the line, a significant instantaneous current change occurs in the line. When the protection device trips, the steady-state current of the line becomes zero. Detecting this sudden change in current value can also determine short circuit in power system and ground fault. Because this kind of indicator does not need to set the alarm threshold in advance, its application range is wider. However, due to the need to monitor the line current in real time, the product consumes more power and has a shorter service life.

fault indicator



3. Application

 Short circuit and ground fault current indicator is a device used to detect short circuit and ground fault. In a ring network distribution system, especially a system that uses a large number of ring network load switches, if a short-circuit fault or ground fault occurs in the next-level distribution network system, the upper-level power supply system must be disconnected within the specified time to prevent major accidents. By using this product, you can mark out the part where the fault occurs. Maintenance personnel can quickly find the faulty section based on the alarm signal of this indicator, and disconnect the faulty section, so as to restore the power supply of the fault-free section in time, which can save a lot of working time and reduce the time and scope of power outage.

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