When to use intermediate relay
1, signal detection, transmission, transformation or processing, the use of intermediate relays, such as the use of metering flicker and so on.
2, the control system output signal and the load side of the electrical isolation; such as the control system output signal for the DC12V, but the load using AC380V power supply.
3, the controller output signal with the load capacity is often limited, in the mA or A level, if there is a need for greater current load, only through the intermediate relay to convert.
4, easy to maintain. When the intermediate relay contacts are damaged due to frequent use, it is easy to replace by simple plug.
When the contactor contact is not enough, you need to use the intermediate relay to change, increase the contact for use.
Conditions for intermediate relays:
⒈ action voltage
Not more than 70% of rated value.
⒉ return voltage
Not less than 5% rating.
⒊ action time
Not more than 0.02S (rated value).
⒋ return time
Not more than 0.02S (rated value).
⒌ electrical life
Relay under normal load, the electrical life of not less than 10,000 times.
⒍ power consumption
DC circuit is not greater than 4W, the AC circuit is not greater than 5VA.
⒎ contact capacity
The current capacity does not exceed 250V, the current does not exceed 1A of the DC sense of load (time constant τ = 5 ± 0.75ms), the disconnect capacity of 50W; voltage does not exceed 250V, the current does not exceed 3A AC circuit is 250VA ( Power factor CosΦ = 0.4 ± 0.1), allowing a long time to connect 5A current.
⒏ insulation resistance
The following parts are measured with an open circuit voltage of 500 V megger. The insulation resistance shall be ≥ 300 MΩ (at room temperature).
① between the conductive terminal and the exposed non-charged metal or shell;
② between moving and static contacts;
③ between the normally open contacts and normally closed contacts;
④ between the contact and the voltage circuit.
⒐ medium strength
The lower part should be able to withstand the specified AC voltage test for 1 minute without insulation breakdown or flashover phenomenon.
① between all conductive terminals and exposed non-charged metal or shell between 2000V / 50Hz;
② between the static and static contacts 1000V / 50Hz;
③ 1000V / 50Hz between the normally open contact (NO on the relay) and the normally closed contact (NC [1] on the relay)
④ 1000V / 50Hz between contact and voltage circuit.
