Purpose:
This relay is a small rated overvoltage relay used in ultra-high voltage protection circuits as a blocking element for directional lateral deviation.

Working Principle:
2.1 The relay consists of a voltage transformer YH, rectification and filtering circuit, trigger circuit, and actuator components.
2.2 Under normal circumstances, the relay conducts BG1, cuts off BG2, and the actuator does not operate. When the applied AC voltage is greater than the setting value of the relay, the trigger flips, that is, BG1 is turned off, BG2 is turned on, and the executing component acts, causing the dynamic contact to close and the dynamic contact to open, completing the relay function.
2.3 The setting of the relay action voltage is achieved using potentiometer R8.
The BY-4A voltage relay has a protruding plug-in structure (T-shaped).
The schematic diagram of the 2.5 BY-4A voltage relay is shown in Figure 1.

Main technical parameters:
3.1 AC rated value: 110V, 50Hz.
3.2 DC rated voltage: 220V, 110V, 48V.
3.3 Setting range: 2-15V.
3.4 Return coefficient: not less than 0.85.
3.5 Action time: The action time at 1.2 times the set point shall not exceed 0.04 seconds.
3.6 Action value variation: Any set value should not exceed 6%.
3.7 DC voltage variation: It is allowed to vary within the range of 80-110% at 220V and 110V, and within the range of 90-110% at 48V. The relay should be able to work normally.
3.8 When the ambient temperature is -10. ~+50. When the range changes, the difference between the action value of the relay at any set point and the action value at a temperature of+20 ℃ should not exceed ± 10% of the latter.
3.9 Contact form: one pair of movable contacts, one pair of movable contacts.
3.10 Contact breaking capacity: In a DC inductive load current with a voltage not exceeding 220V and a current not exceeding 0.2A (time constant not exceeding 5 × 10-3s), the breaking capacity is 25W, and in an AC circuit it is 30VA.
3.11 Electrical lifespan: 5000 cycles.
3.12 Power consumption: Under rated voltage, the AC circuit power shall not exceed 6VA;
DC circuit 220V not exceeding 6W;
110V not exceeding 4W;
48V is not greater than 2W.
3.13 Weight: Approximately 1kg.

Wiring diagram behind the relay:
The internal wiring diagram of BY-4A voltage relay is shown in Figure 2.



Relay external dimensions and opening dimensions:
The appearance and installation dimensions of BY-4A voltage relay are shown in Figure 4 of the universal structural system.

Ordering instructions:
4.1 Relay name, model, and quantity.
4.2 DC rated voltage.