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:
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)
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).
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.