
B-63943EN/02 3.INSTALLATION
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3.5.4 Noise Suppressor
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.
Notes on selecting the spark killer
• 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.)
• 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) :
20
to
10
22
II
(µF)
I : Current at stationary state of the coil
Equivalent circuit of the spark killer
RC
Spark killer
Spark killer
Motor
C relay
Mount the noise eliminator near a motor or a relay coil.
NOTE
Use a CR-type noise eliminator. Varistor-type
noise eliminators clamp the peak pulse voltage but
cannot suppress a sharp rising edge.