Yaskawa G7 Drive - Manual (Page 50)

Wiring Main Circuit Terminals
2-
19
Do Not Use an Electromagnetic Switch
Never connect an electromagnetic switch (MC) between the Drive and motor and turn it ON or OFF during
operation. If the MC is turned ON while the Drive is operating, a large inrush current will be created and the
overcurrent protection in the Drive will operate.
When using an MC to switch to a commercial power supply, stop the Drive and motor before operating the
MC. Use the speed search function if the MC is operated during operation. If measures for momentary power
interrupts are required, use a delayed release MC.
Installing a Thermal Overload Relay
This Drive has an electronic thermal protection function to protect the motor from overheating. If, however,
more than one motor is operated with one Drive or a multi-pole motor is used, always install a thermal relay
(THR) between the Drive and the motor and set L1-01 to 0 (no motor protection). The sequence should be
designed so that the contacts of the thermal overload relay turn OFF the magnetic contactor on the main circuit
inputs.
Installing a Noise Filter on Output Side
Connect a noise filter to the output side of the Drive to reduce radio noise and inductive noise.
Fig 2.8 Installing a Noise Filter on the Output Side
Countermeasures Against Inductive Noise
As described previously, a noise filter can be used to prevent inductive noise from being generated on the
output side. Alternatively, cables can be routed through a grounded metal pipe to prevent inductive noise.
Keeping the metal pipe at least 30 cm (approximately 1 foot) away from the signal line considerably reduces
inductive noise.
Fig 2.9 Countermeasures Against Inductive Noise
Inductive Noise: Electromagnetic induction generates noise on the signal line, causing the controller to malfunction.
Radio Noise: Electromagnetic waves from the Drive and cables cause the broadcasting radio receiver to make noise.
IM
MCCB
Power
supply
Drive
Noise
filter
Signal line
Inductive
noise
Radio noise
AM radio
Controller
IM
MCCB Power
supply
Drive
Signal line
Controller
Metal pipe
30 cm min.
(1 ft.)