
G. SERVO AMPLIFIER NOISE
PROTECTION
B–65162E/03
APPENDIX
630
<<Possible causes>>
The transformer on a utility pole is shared by neighbors, and noise is
being radiated from the power supply wiring. Noise may also be
conducted through the power supply line.
<<Measures>>
1 Install a noise filter (LC filter) on the power supply.
2 Feed power to the neighbors from a separate utility pole.
<<Notes>>
D When installing a noise filter, minimize the length of the wiring
between the filter and servo amplifier.
(3) Refrigerator
<<Symptoms>>
When the spindle rotation is decelerated, the motor of a refrigerator
in the neighborhood makes an abnormal sound.
<<Possible causes>>
The transformer on a utility pole is shared by neighbors, and voltage
distortion is caused by power regeneration at spindle deceleration.
<<Measures>>
1 Feed power to the neighbors from a separate utility pole.
2 Review the power supply capacity.
<<Notes>>
D A plant located in a dense residential area often takes its power
from a utility pole that also supplies power to neighboring houses
(light power sharing), such that the power supply capacity of the
system may be insufficient. In such a case, a larger power
distortion may result, thus affecting the power being fed to
neighboring houses.
(4) Telephone
<<Symptoms>>
When the machine is operated, the telephone of a house across the
street is affected by noise.
<<Possible causes>>
When a high–frequency current from the servo amplifier or motor
returns through the ground of the transformer of the utility pole, it
flows through the ground shield of the telephone line, generating
noise by electrostatic induction.
<<Measures>>
1 Feed power to the neighbors from a separate utility pole.
2 Insert a capacitor on the grounding wire on the servo amplifier
power supply side.
<<Notes>>
D Noise consists of voice frequency components, so that a noise
filter (LC filter) may have no effect.
D Inserting a capacitor on a grounding wire increases the leakage
current, so that the ground fault interrupter may function.