Relay has several roles, one is to expand the number of contacts, the general contactor contact number is limited, not enough time to use the intermediate relay expansion
Second, capacity, such as temperature controller, pressure gauge, level gauge, etc., their contact capacity is not allowed through the high current, it is necessary to use the relay transfer
Third, some special features, such as delay, etc., other things can not be replaced
PLC can be used to replace Oh, but the cost is too high!
Relay is a kind of switch, some places can not, but for example, if you say that there is now a large load of electrical appliances, such as 20,000 W electric stove, do not you use the air switch directly up to help you, you die a small sample , With a middle relay can be resolved, with DC or AC small voltage, such as 5V, you can control, simple, safe, there are a variety of relays, such as delay relay, you can set the time through Off, you do not have that.
Relay is a kind of switch, some places can not, but for example, if you say that there is now a large load of electrical appliances, such as 20,000 W electric stove, do not you use the air switch directly up to help you, you die a small sample , With a middle relay can be resolved, with DC or AC small voltage, such as 5V, you can control, simple, safe, there are a variety of relays, such as delay relay, you can set the time through Off, you do not have that
