Shock-hazard Protection
Leakage current
Leakage current via the PE conductor results from the combination of equipment and cable leakage currents. The leakage current frequency pattern includes a number of frequencies, whereby the
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Since the leakage current to PE is more than 3.5mA, in compliance with IEC 61800-5-1 the PE connection must either be doubled or a connecting cable with a cross-section >10mm² must be used. Use the PE terminal and the PE connection screws in order to fulfill this requirement. |
Use the following measures to minimize leakage currents:
- Reduce the length of the
- Use low capacitance motor cables
Residual current protective device (RCD)
In conformity with IEC 60364-4-41 – Regulations for installation and IEC 60204 – Electrical equipment of machinery, you can use residual current protective devices (RCDs) provided the requisite regulations are complied with.
The servo drive is a 3-phase system with a B6 bridge. Use RCDs which are sensitive to all currents in order to detect any DC fault current.
Rated residual currents in the RCDs:
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10 to 30 mA |
Protection against "indirect contact" (personal fire protection) for stationary and mobile equipment, as well as for "direct contact". |
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30 to 50 mA |
Protection against "indirect contact" (personal fire protection) for stationary equipment |
Recommendation:
Protect each servo drive individually using a 30mA RCD which is sensitive to all currents to secure against direct contact (with motor cables shorter than 5m).
If you use a selective RCD, the more intelligent evaluation process will prevent spurious tripping of the RCD.
Isolating transformers
When protection against indirect contact is absolutely essential despite a higher leakage current, or when an alternative form of shock-hazard protection is sought, the servo drive can also be operated by using an isolating transformer. Use a ground-leakage monitor to detect short circuits.
Note: Keep the length of wiring between the transformer and the servo drive as short as possible.
