1. Coil voltage

The coil voltage should be selected according to the rated voltage in design. If not, please refer to the temperature rise curve for selection. Using any coil voltage lower than the rated working voltage will affect the operation of the relay. Relay manufacturers pay attention to the coil operating voltage refers to the voltage applied between the coil terminals, especially when using an amplifier circuit to excite the coil, be sure to ensure the voltage value between the two terminals of the coil. The little guy in the relay manufacturer believes that, on the contrary, the performance of the product will be affected when the high rated working voltage is exceeded. Excessive working voltage will cause the coil temperature to rise too high, especially at high temperatures, which will damage the insulating material. It will also affect the safety of the relay.

For magnetic latching relays, the excitation (or reset) pulse width should not be less than 3 times the pull-in (or reset) time, otherwise the product will be in a neutral state. When a solid-state device is used to excite the coil, the withstand voltage of the device should be at least 80V and the leakage current should be small enough to ensure the release of the relay.

2. Transient suppression

When the relay coil is de-energized, an inverse peak voltage that is more than 30 times higher than the rated working voltage of the coil can be generated on the coil, which is extremely harmful to the electronic circuit. Usually, parallel transient suppression (also called peak clipping) diodes or resistors are used. The method should be suppressed so that the inverse peak voltage does not exceed 50V, but the parallel connection of the diode will prolong the release time of the relay by 3 to 5 times. When the release time requirement is high, a suitable resistor can be connected in series at one end of the diode. Excitation power supply: under 110% rated current, power supply adjustment rate ≤10% (or output impedance <5%>

3. Parallel and series power supply of multiple relays

When multiple relays are powered in parallel, the relay with high inverse peak voltage (that is, high inductance) will discharge to the relay with low inverse peak voltage, and its release time will be prolonged. Therefore, each relay is controlled separately and then connected in parallel to eliminate mutual influence. Do not use relays with different coil resistance and power consumption in series for power supply, otherwise the relays with large coil currents in the series circuit will not work reliably. Only relays of the same specification and model can be connected in series, but the inverse peak voltage will increase and should be suppressed. According to the voltage division ratio, series resistors can withstand the part of the voltage that is higher than the rated voltage of the coil of the relay.