Use Of Residual Current Protective Devices - Siemens SENTRON Instructions Manual
Residual current protective devices
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Notes on installation and use
5.1.2 Use of residual current protective devices
Residual current protective devices can be combined with any other protective
devices. Even if other protective measures are already installed in an existing
system, residual current protection can still be used for this system or parts of
it. Almost any type of protective measure can be converted to residual current
protection with comparatively little effort.
According to the standard DIN VDE 0100-530, it is permissible, where a residual
current protection device with a rated residual current of IΔn ≤ 30 mA is being
used, to also use this simultaneously to provide fault protection in the form of
automatic disconnection of the power supply and additional protection in the
event of direct contact. However, because this additional protection by means
of residual current protective devices with a rated residual current that does not
exceed 30 mA is envisaged as additional protection for the event that precautions
for basic protection and/or precautions for fault protection are not successful, it
is nevertheless recommended that the protective functions be split up among
different devices in order to fulfill both of these protection goals. In order to
achieve maximum availability and operational safety, the circuits must be divided
up appropriately among several residual current protective devices. These require-
ments are specified in different documents:
• According to DIN VDE 0100-300 (VDE 0100-300):1996-01, the circuits must be
divided up in order to avoid hazards, limit the consequences of faults, facilitate
inspection, testing and maintenance and take into account hazards which can
be caused by a fault in only one circuit, e.g. lighting failure.
• TAB 2007 (Technical Connecting Conditions) states that when circuits are
divided up, connection points for items of currentusing equipment be assigned
to a circuit in such a way that automatic tripping of the protective device
assigned to this circuit in the event of a fault or necessary manual disconnec-
tion from the power supply only cause a part of the customer's installation to
be disconnected from the supply.
This means that: except when selective residual current protective devices are
used, the circuits are to be divided up in such a way that tripping of a residual
current protective device does not lead to the failure of all circuits.
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