The relay is a device with a set of electronic control devices and the power part of the load. This device is widely used in control circuits as well as in automatic devices due to its ability to control high output powers with low power input signals. Also, this device switches circuits and records the deviation from the required level.
Instructions
Step 1
Determine which relay characteristics you need. First, find the required pickup value, which is the sum of the input parameter at which the relay picks up. Second, select the power of the relay. Pay special attention to its very minimum power, which must be supplied to the working element. It is necessary to transfer the relay from the initial state to the working one.
Step 2
Calculate the controllable power required by the relay for your specific application. Control powers are divided into relay circuits: high power (power relay), medium power (no more than 100 W) and low power (up to 25 W).
Step 3
Find out how long it will take for the relay to operate, that is, what will be the time interval between the moment the signal is applied and the beginning of its direct effect on the circuit. Relays for this type of characteristics are divided into time relays, delayed relays and high-speed relays.
Step 4
Pay special attention when choosing the very design of the relay, since the power will also depend on it. Look at the characteristics that relate to the disadvantages of this device, namely: the size of the mechanical resource, the speed of work, the amount of interference during the circuit, the amount of the electrical resource. Look at what is the value of the operating voltage in the relay winding, it must necessarily correspond to the data in the technical documentation.
Step 5
Give preference to relays with high operating voltage characteristics. During a short-term supply of increased voltage to the winding, mechanical overvoltage may occur in the contact group. Be sure to pay attention to the value of the switched current and the value of the expected load, the main power of the relay will depend on these characteristics.
