What is the purpose of monitoring the working principle of a relay?
Surveillance relays are a commonly used electromagnetic relays, and voltage supervisory relays are used for voltage protection and control of electric drive systems. The coil connected in parallel to the main circuit, sensing the main circuit of the line voltage; contact connected to the control circuit for the implementation of components. According to the size of the pull-in voltage, voltage relays can be divided into over-voltage relays and undervoltage relays.
In fact, it can not be called it (monitor the relay), a little bit of its human nature, and its working principle and the general working principle is very similar to its principle: when in a composite circuit inside, if the first-stage circuit power, And the relay can continue to power the second stage of the circuit (the premise: the rest of the circuit are closed), and the relay inside is equivalent to the battery, before the first level is not disconnected, is equivalent to charge it, when the first Level off, this time you are talking about monitoring, monitoring to the first level off, so when it began to work for the second level to provide power!
Relay, also known as intermediate relay (relay): for relay protection and automatic control system to increase the number and capacity of contacts. It is used to pass the intermediate signal in the control circuit. The structure and principle of the intermediate relay are basically the same as those of the AC contactor. The main difference from the contactor is that the main contact of the contactor can pass through the high current and the contact of the intermediate relay can only pass through the small current. Therefore, it can only be used in the control circuit. It is generally no main contact, because the overload capacity is relatively small. So it is all with auxiliary contacts, the number of more. The new national standard for the definition of intermediate relay is K, the old national standard is KA. Usually DC power supply. A few use AC power.
These two relays each have their own characteristics, respectively, applied to different occasions, if you want to say the difference, the monitoring relay is built-in detection circuit, active control, intermediate relay need external control signal passive control
