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5. Peripheral Devices
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5-3 Selection of earth leakage breaker
When installing an earth leakage breaker, select the breaker on the following basis to prevent the
breaker from malfunctioning by the higher frequency earth leakage current generated in the servo drive
unit.
(1) Selection
Obtaining the earth leakage current for all drive units referring to the following table, select an earth
leakage breaker within the "rated non-operation sensitivity current".
Usually use an earth leakage breaker for inverter products that function at a leakage current within
the commercial frequency range (50 to 60Hz).
If a product sensitive to higher frequencies is used, the breaker could malfunction at a level less
than the maximum earth leakage current value.
Earth leakage current for each drive unit
Drive unit Earth leakage current Maximum earth leakage current
MDS-R-V1-20 to 80 1mA 2mA
MDS-R-V2-2020 to 8080 1mA 4mA (for two axes)
(Note1) Maximum earth leakage current: Value that considers wiring length and grounding, etc.
(Commercial frequency 50/60Hz)
(2) Measurement of earth leakage current
When actually measuring the earth leakage current, use a product that is not easily affected by the
higher frequency earth leakage current. The measurement range should be 50 to 60Hz.
POINT
1. The earth leakage current tends to increase as the motor capacity increases.
2. A higher frequency earth leakage current will always be generated because the
inverter circuit in the drive unit switches the transistor at high speed. Always
ground to reduce the higher frequency earth leakage current as much as
possible.
3. An earth leakage current containing higher frequency may reach approx.
several hundreds of mA. According to IEC479-2, this level is not hazardous to
the human body.
4. For safety, ground the machine with Class C (former class 3) grounding.