OCEM IRM Operation And Maintenance Manual page 12

IRM
2.1.1 Generality
The device IRM performs measure of the insulation resistance of the circuit airport series through the periodic
application of a voltage of about 800 V
ground. The measuring interval can be customised (default: 60 sec). The device IRM can be inserted on the
series circuit independently on the type of regulator unit and without the need to make changes to the circuit. A
disconnector switch easily accessible allow the supply control.
A LED display positioned on the front of the device IRM allows to locally view the measured insulation resistance
value AND alternatively the current values (and voltage, optional) on the series circuit, and the main alarms. All
the threshold values (pre‑alarm and alarm) can be customised.
The internal connection between the measurement card and the interface card is realized through a pair of optical
fibres.
The device IRM allows the remote monitoring (optional) of the measured values.
The device is suitable at monitoring series circuits powered by power regulator units not higher than 30 kVA/6.6 A,
in the measuring field 10 kΩ ÷ 500 MΩ.
2.1.2 Construction detail
The device consists of a case in zinc‑coated steel, painted with thermosetting epoxy powders (colour RAL 7032).
The internal sides of the device are segregated by panels in polycarbonat, removable only in safety conditions for
the operator (as indicated on the monitoring plates).
The intake and outlet of the cables of the series circuit and of the supply circuit is foreseen from below through
suitable cable gland. The protective conductor (min. 10 mm2) must be attested through a terminal stud to the
screw M8 present on the container. On the bottom in addition there are connectors or cable entry systems for the
connection of signals (optionals).
The device is predisposed for the wall fastening through suitable fastening system through screws and plugs (not
provided). A template 330x420 mm allows an easier realization of support holes properly aligned.
2.1.3 Optional devices
●
Series circuit rated voltage reading: the device allows the measuring of the voltage on the series circuit,
making them available on the local display and on the remote reading.
●
Electromechanical remote signalling: a terminal board on the card or a connector make available the reverse
contacts (NC, C, NA) to repeat the WARNING, ALARM and MANUAL status.
●
IRMS remote control option: is possible remote monitoring of the values measured from the device, through
a LONTALK network (standard ISO/IEC 14908-2). A connector type HARTING 5 pin (2 conductors twisted
pair + shield) ‑supplied‑ allows to easily connect the device to the network.
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to an end of the series circuit by measuring the leakage current to the
DC
UT-MT-0930_1.3_220421 (EN)
Operation and Maintenance Manual