The BLD-20 high-voltage leakage protection relay (hereinafter referred to as the relay) has a power directional leakage protection function. It can be used in conjunction with vacuum low oil and SF6 mining general distribution switches (devices) or vacuum circuit breakers for selective protection against leakage (or grounding) in 3-10KV medium point ungrounded systems of the power supply system.

characteristic
Adopting the power directional principle, it operates reliably. The internal circuit components have the advantages of easy selection, high sensitivity, strong selectivity, and stable performance. Choose a small sealed relay as the fault memory component, with power indication and a light display after the fault, to quickly and accurately diagnose the fault. Install using the latest guide rails or fixed installation. The test and reset buttons can be externally connected or not, making them very convenient to use.

Usage conditions of BLD-20 high-voltage leakage protection relay
1. The altitude shall not exceed 3000 meters.
2. The ambient temperature should not exceed+40 ℃ and should not be lower than -20 ℃.
3. The relative temperature of the surrounding air is not greater than 95%. (When the ambient temperature is+25 ℃).
4. Without explosion-proof casing, it cannot be used in environments with explosive hazards.
5. In a gas environment that does not damage metals or corrode insulation.
6. A place without dripping or water intrusion.

Main technical data
1. The primary zero sequence current of the leakage protection sensitivity relay is 0 1A. The secondary zero sequence voltage is 3V ± 0.4.
2. Primary zero sequence current grading: 0.1, 0.3, 0.5, 1.0, 3.0, 6.0 (A) with an error not exceeding ± 10%.
3. Protection action time: 0.1, 0.5, 1.0, 1.5, 2.0, 5.0 (S) with an error not exceeding ± 10%.
4. Rated power supply voltage: 100V, 50Hz. This device can operate normally within the range of 100V ± 20%.
5. Output contact life: 115VAC × 1A (resistive load) 100000 times. 28VDC × 2A (resistive load) 100000 times.

Working principle of BLD-20 high-voltage leakage protection relay
Leakage protection consists of zero sequence current circuit, zero sequence voltage circuit, phase comparison, time division, and relay locking unit. When a leakage or grounding occurs in the circuit, zero sequence voltage exists simultaneously. The phase comparison is carried out through the current circuit and voltage circuit respectively, and then divided into different time intervals to activate the relay and display the indicator light.

Structural appearance
1. This protective device uses an ABS plastic shell, and its appearance and installation dimensions are shown in Figure 1.
2. Dimensions: 90 × 116 × 50mm.
3. Net weight: ≤ 0.5Kg.

Inspection before installation and use
1. Appearance inspection: Check whether the relay model and accessories are complete, and the appearance should have no obvious damage or deformation. The indicator lights should be complete and securely fastened.
2. Electrical performance inspection shall be conducted according to BLD-20 external wiring diagram 2 for wiring. Use the test button for testing, the unit should operate normally, and the indicator light should display a light. Random inspection of all major technical data should meet the requirements.

Installation, use and maintenance
1. Each unit should be positioned as required.
2. After installation, the test button on the power distribution device must be powered on for testing, and the action should be normal.
3. Installation and use of zero sequence current transformer: Zero sequence current transformer is a key component of leakage protection. The terminal face is facing the power supply side of the busbar, with K connected to pin 8 of the protection device, S connected to pin 9 of the protection device, and D connected to pin 10 of the protection device. It cannot be reversed.
4. It is strictly prohibited to use a megohmmeter to test the circuits inside this device.
5. When repairing welded components, a soldering iron with a power of less than 45W should be used to prevent component burnout.
6. To replace the semiconductor components on this device, it must be tested and screened before use.
7. In order to keep the protective device in normal working condition, regular tests and inspections should be conducted.