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System description
3.3 Functionality UMC107E-..
3.3.1
The UMC107E-... changeover and monitoring module
If the preferred supply should fail, the UMC107E-.. ensures safe changeover of the
power supply:
1. In normal condition (fault-free condition), the preferred supply (line 1) is connected via contac-
tor K1 and mechanically latched. This makes it impossible for the IT supply to fail on account of
defective contactor coils, torn lines to the contactor coil, or a failure of the control voltage.
2. If the voltage at the end of the preferred supply falls below the set value or exceeds a value of
115 % x U
, the module automatically changes over to the second supply (line 2): Once the set
n
response time t(off) has elapsed, K1 is disconnected and, following the set idle time t(K1-2), K2
is connected and latched.
3. On voltage recovery, switching back to the preferred supply source occurs automatically after
the set return transfer time t(on) has elapsed: K2 is disconnected and, following the set idle
time t(K1-2), K1 is connected and latched.
The response time t(off), the idle time t(K1-2) and the return transfer time t(on) of
the UMC107E-.. can be set and must be adjusted according to the requirements
of the specific application case, the short-circuit calculation and the require-
ments of IEC 60364-7-710:2002-11, sections 556.5.2.2, 556.7 and 556.8 and DIN
Warning
VDE 0100-710 (VDE 0100 Part 710):2002-11, section 710.537.6 (automatic
changeover modules) (see chapter 5. "Commissioning, settings and testing").
The settings made at the factory ensure a changeover period of t = 0.5 seconds and switching
back within five seconds on voltage recovery on the preferred supply. Therefore, the
UMC107E-.. can also be used in IT systems with a requirement for a changeover period t =
0.5 seconds (IT systems with operating theatre lighting circuits, endoscopic field illumination
in operating theatres, or other essential sources of light, etc.).
If the control device detects a supply line failure or a fault, a message appears in the LC dis-
play, the "ALARM" LED lights up, the alarm relay switches, and this alarm is transmitted to
other Bender devices (such as alarm indicator and test combinations) via the BMS bus.
3.3.2
IT system monitoring
Insulation monitoring
The insulation monitoring device measures the insulation resistance in AC IT systems which
may also contain DC circuits. The adaptation to the system leakage capacitances takes place
automatically.
Load current measurement
The load current is measured via the measuring current transformer STW2.
Temperature measurement
The temperature in the transformer winding is measured via PTC thermistors.
Evaluation
If any of the measured values does not fall within the limits, an alarm (common alarm) is
triggered. The "ALARM" LED lights up, the alarm relay switches and a message appears in
the LC display of the insulation monitoring device. This alarm is transmitted to other Bender
devices (such as an alarm indicator and test combination) via the BMS bus.
TGH1322en/06.2009
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