Intermediate relay: for relay protection and automatic control system, in order to increase the number and capacity of the contact. It is used to transfer the intermediate signal in the control circuit. The structure and principle of the intermediate relay and AC contactor is basically the same, with the main difference lies in: the main contact of the contactor contactor can by high current, and can only contact the intermediate relay through small current. So, it can only be used in a control circuit. It is generally not the main contact, because the overload capacity is relatively small. So it is all the more the number of auxiliary contact. The new national standard definition of intermediate relay is K, the old GB is KA. The general is a DC power supply. The use of AC power supply of minority.
parameter
The operation voltage is not greater than 70% ratings.
The return of not less than 5% of rated voltage.
C. action time: not more than 0.02S (ratings).
The return time: not more than 0.02S (ratings).
The life of electric relay under the normal load, the electrical life of not less than 10 thousand times.
The DC power consumption: less than 4W, the AC circuit is not greater than 5VA.
But contact capacity: in voltage not exceeding 250V, current less than 1A DC with load (time constant tau = 5 + 0.75ms), disconnect capacity is 50W; in voltage not exceeding 250V, current does not exceed 3a in an AC circuit for 250VA (power factor cos phi = 0.4 + 0.1), allows the always connected to the 5A current.
The insulation resistance:
The following parts with open circuit voltage 500V megger insulation resistance should be greater than or equal to 300M (at room temperature).
Between 1. The conductive terminal and the exposed electriferous or shell; (2), a static contact between; the normally open contact and normally closed contact between; (4) contact with the voltage loop.
The dielectric strength:
The site should be able to withstand the specified AC voltage test for 1 minutes without insulation breakdown or flashover phenomenon.
All the conductive terminals and non exposed between the charged metal or shell 2000V/50Hz;
1000V/50Hz between the dynamic and static contacts;
The normally open contact (relay on NO) and normally closed contact (relay NC) 1000V/50Hz;
The contact between 1000V/50Hz and voltage circuit.
And anti-jamming performance: relay interference shall comply with the relevant provisions of the DL478-92 the static relaying protection and automatic device for general technical conditions ".