
7.INSTALLATION CONDITIONS AND NOTES FANUC AC SERVO AMPLIFIER β series B-65232EN/03
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7.3.3 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. In general, to reduce this pulse voltage, a
spark killer is used in AC circuits, while a diode is used in DC
circuits.
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:
Resistance (R) : Equivalent DC resistance of the coil
Capacitance (C) : I
2
/10 to I
2
/20 (
µ
F)
I : Current at stationary state of the coil (A)
Equivalent circuit of
the spark killer
AC relay
Spark killer
Spark killer
Mount the noise
eliminator near a motor
or a relay coil.
Motor
CAUTION
Use a CR-type noise eliminator. Varistor-type noise
eliminators clamp the peak pulse voltage but
cannot suppress a sharp rising edge.
Diode
Diode (used for direct-current circuits)
Diode
Use a diode which can withstand a voltage
up to two times the applied voltage and a
current up to two times the applied current.
DC relay