Electrical Installation
3
3.10 Drive Wiring Protection
YASKAWA SIEPC71061753C GA500 Technical Manual 105
3.10 Drive Wiring Protection
◆ Installing a Residual Current Monitoring/Detection (RCM/RCD)
When the drive output switches at high speeds, it causes high frequency leakage current. To prevent electrical
shock and fires caused by ground fault protection that is not sufficient, install an RCM/RCD.
Use a high frequency RCM/RCD at the power input side of the drive and make sure that each drive has a
minimum cumulative sensitivity amperage of 30 mA. The specialized breaker detects only the leakage current
from frequency bands that are dangerous to humans.
If a device does not have protection against high frequencies, high frequency leakage currents can cause the
device to malfunction. If you have a malfunction on a device that is not protected, decrease the carrier frequency
of the drive, switch to a better breaker, or use an RCM/RCD with a minimum cumulative sensitivity amperage of
200 mA for each drive.
These conditions can have an effect on leakage current:
• Drive capacity
• Carrier frequency
• Wiring distance and types of motor cables
• EMI/RFI filter
To prevent damage and injury to personnel and drives, use a high-frequency RCM/RCD that is rated for AC and
DC power supplies.
Note:
Yaskawa recommends these RCMs/RCDs, which are designed to operate with high frequencies:
• Mitsubishi Electric Corporation, NV series
• Schneider Electric, NS series
You can use a molded-case circuit breaker (MCCB) as a replacement for an RCM/RCD that is upstream in the
power supply system.
◆ Installing a Molded-Case Circuit Breaker (MCCB) or Residual Current Monitor/
Device (RCM/RCD)
Install a molded-case circuit breaker (MCCB) or a residual current monitor/device (RCM/RCD) for line
protection between the power supply and main circuit power supply input terminals R/L1, S/L2, and T/L3. The
MCCB or RCM/RCD gives overload protection and also prevent damage to the main circuit and the devices that
are wired to the main circuit.
Use the information in this section to select the correct MCCB or RCM/RCD and to safely connect the device.
• The capacity of the MCCB or RCM/RCD must be 1.5 to 2 times the rated output current of the drive. Use an
MCCB or RCM/RCD as an alternative to overheat protection (150% for one minute at the rated output current)
to prevent drive faults.
• When you connect more than one drive or the drive and other device to an MCCB or RCM/RCD, refer to Figure
3.57, use a magnetic contactor (MC), and set a sequence that de-energizes the drive when it outputs errors.
A - Power supply B - Drive
Figure 3.57 Connect an MCCB
WARNING! Electrical Shock Hazard. Use an MCCB, RCM/RCD, or Magnetic Contactor (MC) to de-energize the drive before
you wire the main circuit terminal. If the main circuit terminal is energized during wiring, it will cause serious injury or death.
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