Precautions for using pcb relay

The pcb relay is a miniature electronic control device, in which the circuit board makes the circuit miniaturized and intuitive, which plays an important role in the mass production of fixed circuits and optimizing the layout of electrical appliances. The relay has a control system (also called an input loop) and a controlled system (also called an output loop). It is usually used in automatic control circuits. It is actually a kind of "automatic switch" that uses a smaller current to control a larger current. ". Therefore, it plays the role of automatic adjustment, safety protection, and conversion circuit in the circuit.

Precautions for use:

1. When used in an AC inductive load, high transient voltage and surge current are applied to the output terminal, which may cause the pcb relay to be turned on or damaged. It is usually necessary to connect a voltage control device with a specific clamping voltage to the output terminal, such as Two-wire Zener diode or Varistor (MOV). The varistor is recommended to be 1.6-1.9 times the rated voltage;
2. For DC inductive loads, such as solenoids, electromagnets, and solenoid valves, a freewheeling circuit must be used to suppress the back electromotive force generated during shutdown. The simpler method is usually to connect a diode in anti-parallel with the load, but this The circuit will affect the release time of inductive loads such as electromagnetic relays, contactors, electromagnets, solenoid valves, etc. The better line is a diode and a Zener diode in reverse series or a diode and a resistor in series and then reverse to the load. in parallel.
3. When controlling a small current load close to the minimum load current, a virtual load resistor must be connected in parallel with the load to reduce the leakage current at the output terminal and produce a higher residual voltage on the load.
4. When the pcb relay is welded and installed, the welding temperature must be controlled below 260 degrees Celsius, and the welding time must be controlled below 5s.
5. In order to avoid the temperature rise of the pcb relay exceeding the allowable value, the heat dissipation effect and installation position should be considered when designing the application. When two or more pcb relays are installed side by side, a proper distance should be left.