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6.3
Connection Types and Connection Examples
6.3.1
Using SICAM MMU in the Power Systems IT, TT and TN
The following operating conditions must be observed when using SICAM MMU in the various power systems:
Table 6-3
Voltage Measurement Inputs
of SICAM MMU acc. to
Ordering Information
(see chapter 2.2)
Potential divider
Galvanic isolated
NOTICE
Concerns only SICAM MMU with voltage measuring inputs via voltage dividers
In IT systems, SICAM MMU cannot be connected directly because the measuring voltage is measured against
the protective ground connection (PE) and the input impedance of the device causes a leakage current to
ground. The leakage current can cause the insulation monitoring in IT systems to pick up.
Non-observance can result in property damage.
•
Make sure that the maximum permissible voltage at the inputs of SICAM MMU to ground V
(347 V for UL conditions) is not exceeded (e.g. in the case of a single-phase-to-ground fault).
•
In IT systems, voltage transformers must be used.
6.3.2
Connection Types
SICAM MMU supports the following connection types:
•
1-phase system
•
3-wire network (balanced)
•
3-wire network (unbalanced), 2 current inputs
•
3-wire network (unbalanced), 3 current inputs
•
4-wire network (balanced)
•
4-wire network (unbalanced)
SICAM MMU 7KG9663, Device Manual
E50417-H1040-C514-A3, Edition 01.2016
SICAM MMU Operating Conditions
Only with voltage
transformers (see ex-
amples chapter 6.3.3)
Yes
6.3 Connection Types and Connection Examples
Power System
IT
TT
Yes
Yes
6 Connection Principle and Applications
TN
Yes
Yes
= 480 V
a-N
59
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