Modify pick up time respone and impulse period of auxiliary relay- how to.

Impulse time and pick up time response of an auxiliary relay can be modified by adding resistor and capacitor. Also the pick-up and drop-out time lag can be modified with an extent of transient protection by adding diode, varistor or thermistor with auxiliary relay.

Resistor and capacitor plug in unit to add with auxiliary relay is provided by the manufacturer as accessories. Care should be taken before inserting them to relay. The recommendation by the manufacturer should be followed.

What is pickup time and impulse period of relay:

Pick up time-The time duration between signal receiving and relay activation can be mentioned as pick up time. Relay activation might be anything the relay is assigned to do like off to on, on to off, sending a signal, initiating an operation, stopping an operation etc.

Impulse period- Some relay do nothing but sending a signal for a brief moment like for mili-second. This time duration is called impulse period.

Impulse storing circuit (impulse lengthening)

When the impulse contact S momentarily makes, the relay picks up and remains picked up for a period the length of which is determined by r, R and C.
impulse storing circuit of auxiliary relay

Impulse shortening circuit

When S makes, the relay R picks up instantaneously and remain a picked up until C is sufficiently charged. The relay then drops out, since the current through r and R falls below the relay drop-out valve. (S remains closed all the time).
impulse shortening circuit of auxiliary relay


Shorter pick-up times with separate series connected resistor

The operating time can be reduced for auxiliary relays by connecting a separate resistor – r in the diagram – in series with the relay coil R. The connection reduces the L/R ratio, i.e. the time constant for the drawn relay coil operating current.
shorter pickup time of auxiliary relay

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