Alle Rechte und Änderungen vorbehalten.
Subject to change without notice. All rights reserved.
© Bender GmbH & Co KG
UMA710-2-xx-ISO-xx, Manual.docx
Issued: 11.Jan.2016
14
3.4.2. Insulation monitoring of the IT-System
Insulation monitoring
The integrated insulation monitoring device measures the insulation resistance on AC IT systems, which
may also contain DC voltage components. Adaptation to the system leakage capacitances occurs
automatically. The measuring time increases as the system leakage capacitances increase.
Load current measurement
The load current on the IT system is measured using an STW2 measuring current transformer.
Temperature monitoring
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 is triggered. A message appears
on the LCD, the "ALARM" LED lights up, the alarm relay trips (if set) and this alarm is forwarded to other
Bender devices (such as an alarm indicator and test combination) via the BMS bus.
Locating current injector
When an insulation fault is detected on an IT system, the integrated locating current injector generates
a defined locating current signal to locate the insulation fault. The locating current is limited to
1 mA. This feature can be switched on or off (see chapter "7.4.4.4 Settings menu 4: IT system").
The locating current flowing between the IT system and earth can cause controller faults in
sensitive parts of the system, such as the PLC or relay. It must therefore be ensured that the
locating current is compatible with the monitoring
3.4.3. Monitoring the device functions
The control circuits are designed in such a way that, even though it is almost certain that a particular fault
will occur, it cannot cause the power supply at the output of the automatic transfer switching device to fail.
The ATICS® also continuously monitors:
The switch position of the switch and coils 1 and 2 of the switch
Power supplies 1 and 2, which supply the electronics from the systems concerned
Internal microcontrollers and memory modules
Important connecting wires, such as:
– Measuring current transformer connection
– Temperature sensor connection
– Power supply and PE connection
For alarm and test combinations, and alarm indicator and operator panels, device failure
monitoring can also be programmed via the BMS bus (necessary for functional safety).
On systems with generator: total power failure possible
If the preferred line fails, the ATICS® starts the generator which is connected to the redundant
line. If the generator does not start, the line downstream of the transfer switching device will be
dead. When the generator is switched off, the ATICS® cannot check the redundant line.
Therefore, regularly test the generator and the changeover function to make sure they are
working properly (see checklist in the Appendix to this manual).
