How to Select an Electromagnetic Relay?

The working principle of electromagnetic relay is that when the electromagnet is energized, the armature is sucked down to make the two contacts, and the working circuit is closed. When the electromagnet loses its magnetism, the spring pulls the armature up, cutting off the working circuit. It is usually used in automatic control circuits. It is actually an automatic switch that uses a smaller current to control a larger current, so it plays the role of automatic adjustment, safety protection, and conversion circuit in the circuit.

How to choose an electromagnetic relay?

Selection of power supply for electromagnetic relay coil

Under normal circumstances, DC relays are mostly used in circuit design, and the type of power supply used by the electromagnetic relay can also be considered according to the characteristics of the control circuit. Secondly, the power consumed by the relay should be considered. If the power supplied to the relay coil is large, and there is enough place for installation, and there is no special requirement for the weight of the relay, a general small relay can be used; if the power supplied to the relay coil in the design Smaller. And the equipment used is portable, general ultra-small relays can be used, for miniature electronic devices, miniature relays are used.

Selection of rated working voltage

When using an electromagnetic relay, first of all, it is necessary to understand the working power supply voltage in the circuit where the relay is located. The working voltage of the relay should be equal to this voltage, or the circuit power supply voltage should be 80% of the working voltage of the relay, which can also ensure the normal operation of the relay, but must not make the circuit work. The power supply voltage is greater than the rated working voltage of the relay, otherwise the relay coil will be easily damaged.

Choice of contact capacity

First of all, the number and form of contacts should be determined according to the characteristics of the circuit controlled by the electromagnetic relay, and then the size of the contact capacity should be selected according to the type of current, voltage and current in the contact control circuit. The size of the contact capacity reflects the voltage applied to the contact and the ability to pass the current through the contact. Generally, the load of the contact should not exceed the capacity of the contact. For example, the nominal capacity of a relay is DC24/10A, then the contacts of this relay can only work in a circuit with a DC voltage of 24V, and the maximum current through the contacts can reach IDA. Contacts may be burned.

Determine the action time and release time of the electromagnetic relay

The action time and release time of the relay should be selected according to the time requirements of the actual circuit for the action of the controlled object. Additional electronic components can also be added to the relay circuit to accelerate or delay the action and release time of the relay to meet different requirements.

Working environment conditions

The following working environment conditions should also be considered when selecting an electromagnetic relay:

1. The temperature and humidity of the environment.
2. The life of the relay needs to work.
3. The magnitude of acceleration and direction of movement when the relay is used on non-fixed equipment, as well as the frequency and amplitude of vibration.