The AC/DC solenoid and relay are used in the power magnetics cabinet.
A high pulse voltage is caused by coil inductance when these devices are
turned on or off.
This pulse voltage induced through the cable causes the electronic circuits
to be disturbed. In general, to reduce this pulse voltage, a spark killer is
used in AC circuits, while a diode is used in DC circuits.
D Use a spark killer consisting of a resistor and capacitor in series. This
type of spark killer is called a CR spark killer.(Use it under AC)
(A varistor is useful in clamping the peak voltage of the pulse voltage,
but cannot suppress the sudden rise of the pulse voltage. FANUC
therefore recommends a CR spark killer.)
D The reference capacitance and resistance of the spark killer shall
conform to the following based on the current (I (A)) and DC
resistance of the stationary coil:
1) Resistance (R) : Equivalent DC resistance of the coil
2) Capacitance (C) :
I : Current at stationary state of the coil
Equivalent circuit of the spark killer
Mount the noise eliminator near a motor or a relay coil.
Use a CR–type noise eliminator. Varistor–type noise
eliminators clamp the peak pulse voltage but cannot
suppress a sharp rising edge.