Luoyang electromechanical school air conditioning and refrigeration class, learning the principles and maintenance methods of various refrigeration equipment. Always holding hands, the teacher teaches one-on-one hand.

1. Basic knowledge

The working principle consists of coils, contacts, guide rails, pins, etc. Contacts are divided into moving contacts and static contacts. The movable contact is fixed on the guide rail, and the stationary contact is connected with the pin. When the coil is not energized, the moving contact and the static contact are disconnected.

When working, the coil is energized, and the coil generates electromagnetic attraction to attract the movement of the street rail, so that the moving contact and the static contact are closed.

Main parameters The main parameters of relay are coil working voltage and contact current. Such as relay model JZC-32F, the working voltage of the coil is DC 12V, the contact current is 5A for AC 250V circuit and 10A for AC 125V circuit.

* * * * There are four pins below, of which two pins parallel to one side are coils, which are driven and controlled by weak current; The two non-parallel pins on the other side are contacts, which are connected to a strong electrical load.

2. Relay measurement method

Measure the coil resistance? Use multimeter resistance to measure coil resistance. The resistance of relay coil varies with the contact current (that is, the power of load), which accords with the characteristics of high power coil resistance and low power coil resistance. For example, the measured resistance of compressor relay coil is about150Ω; The normal resistance of outdoor fan, four-way valve coil and auxiliary electric heating relay coil is 200 ~ 700 Ω.

If the measured coil resistance is infinite, the coil is damaged by an open circuit.