Overvoltage Protection - Siemens S120 Manual

Mains connection and line-side power components

3.5 Overvoltage protection

● The shielded motor cable must not be longer than 50 m.
● Use a separate residual current operated circuit-breaker for each Power Module.
● Ensure that the switching elements (disconnector unit, contactors) for connecting and
disconnecting the drive line-up have max. 35 ms delay time time between the
closing/opening of the individual main contacts.
If no residual current device is used, touch protection can be ensured by means of double
insulation or by isolating the Power Module from the supply system through a transformer.
Residual current monitors (RCM)
Used in conjunction with appropriate circuit-breakers, residual current monitors (RCMs)
provide fire and system protection even at high levels of grounding resistance (in TT
systems, for example). When operating on TT systems for infeed powers exceeding 55 kW,
and with systems that extend across a large area, residual current monitors must be installed
in addition to the appropriate circuit-breakers.
Fire hazard and danger of a plant standstill when residual currents occur
Residual currents in the power supply that are not detected can cause fires and failures in
the entire system.
• Always install residual current monitors in conjunction with suitable circuit-breakers.
Note the points below when using residual current monitors:
● Use only AC/DC-sensitive RCM type B devices with delayed tripping that guarantee
reliable tripping even for smoothed DC residual currents.
● Connect parts of the power drive system and the machine that can be touched to the
system's protective conductor.
● Do not route the protective conductor through the measuring current transformer because
this would cancel its protection function.
3.5 Overvoltage protection
To protect the units against line-side surge voltages, you are advised to install an
overvoltage protection device directly at the infeed point (upstream of the main switch). To
comply with the requirements of CSA C22.2 No. 14-05, a type VZCA or VZCA2 surge
arrester is absolutely mandatory. The Raycap company has suitable surge arresters.
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WARNING
Manual, (GH6), 04/2014, 6SL3097-4AL00-0BP4
AC Drive