ID 442426.04 89WE KEEP THINGS MOVING
Connection
7
Manual SD6
7.2.2.2 Residual current safety device
STOBER devices can be protected with a Residual Current protective Devices
(RCD) to detect residual currents. Residual current protective devices prevent
electrical accidents, especially ground fault through the body.
They are generally distinguished according to their triggering limit and
suitability for detecting different types of residual current.
Depending on the function, stray currents may occur when operating drive
controllers. Stray currents are interpreted as residual currents by residual
current protective devices and may therefore lead to false triggering.
Depending on the relevant power supply connections, residual currents may
occur with or without a DC current component. Because of this, you should
take into consideration both the height and also the shape of the possible stray
or residual current when selecting a suitable RCD.
DANGER!
Electric shock hazard!
The combination of single-phase drive controllers and residual current
protective devices type A or AC can lead to false triggering of the RCDs.
Stray currents with a DC current component may occur in 3-phase drive
controllers.
Always protect single-phase drive controllers with residual current
protective devices type B, sensitive to all currents, or with type F, sensitive
to mixed currents.
Always protect 3-phase drive controllers with residual current protective
devices type B, sensitive to all currents.
False triggering – causes
Depending on stray capacitances and asymmetries, stray currents up to 40 mA
may occur during operation. Undesirable false triggering occurs
• ... when drive controllers to the supply voltage.
This false triggering can be rectified by using short-time delayed (super-
resistant), selective (delayed switch-off) residual current protective devices
or RCDs with increased trigger current
(for example 300 or 500 mA).
• ... Due to higher frequency stray currents for long motor cables under
normal operating conditions:
This false triggering can be rectified for example using low-capacitance
cables or output deraters.
• ... due to unbalances in the supply network.
This false triggering can be rectified for example using an isolating
transformer.
Installation
DANGER!
Electric shock hazard!
Stray and residual currents with a DC current component can restrict the
functionality of residual current protective devices types A and AC.
Always follow the installation instructions for the protective devices you are
using.
Information
Check whether the use of residual current protective devices with
increased trigger current as well as with short-time delayed or
delayed switch-off trigger characteristics are permitted in your
application.
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