Page 129 - EPR Catalog 2015

Insulation monitoring relays for unearthed supply systems
Benefits and advantages, Applications
Application / monitoring function CM-IWx
The CM-IWx serve to monitor insulation resistance in accor-
dance with IEC 61557-8 in unearthed IT AC systems, IT AC
sytems with galvanically connected DC circuits, or unearthed
IT DC systems. The insulation resistance between system
lines and system earth is measured. If this falls below the
adjustable threshold values, the output relay(s) energize or de-
energize. The CM-IWS.x can monitor control circuits (single-
phase) and main circuits (3-phase). Supply systems with volt-
ages Un= 0-400 V AC (45-65 Hz), Un=0-250 V AC (15-400 Hz)
or 0-300 V DC can be directly connected. For systems with
voltages above 400 V AC the insulation monitoring relay with
or without the coupling unit CM-IVN can be used.
Application / monitoring function CM-IWN.x
The CM-IWN.x serves to monitor insulation resistance in
accordance with IEC 61557-8 in unearthed IT AC systems,
IT AC systems with galvanically connected DC circuits, or
unearthed IT DC systems. The insulation resistance between
system lines and system earth is measured. If this falls below
the adjustable threshold values, the output relays switch into
the fault state. The device can monitor control circuits (single- insulation resistance and system leakage capacitance. From
phase) and main circuits (3-phase). Supply systems with
voltages Un = 0-400 V AC (15-400 Hz) or 0-600 V DC can be
directly connected to the measuring inputs and their insulation
resistance being monitored. For systems with voltages above
400 V AC and 600 V DC the coupling unit CM-IVN can be
used for the expansion of the CM-IWN.x voltage range.
Expansion of assortment for the requirements of
decentral eletrical energy sources
ABB‘s insulation monitoring relays from the CM-IWN range
provide higher system leakage capacitances which are neces-
sary especially for solar applications. This expanded product
range covers the requirements of decentral eletrical sources
(e.g. photovoltaic systems).
The range of system leakage capacitances is 20 - 2000 μF.
2CDC 110 004 C0210 | Catalog Electronic Products and Relays 2015 | ABB 2/62
Application / monitoring function CM-IVN 2
The coupling unit CM-IVN is designed to extend the nominal
voltage range of the insulation monitoring relay CM-IWN.1
up to 690 V AC and 1000 V DC. The coupling unit can be
connected to the system to be monitored by means of the
terminals VL+ and VL-. The terminal Vw has to be connected
to the earth potential. The terminals L+, V1+, L-, V1-, VS and
VE have to be connected to the CM-IWN.1 as shown in the
connection diagrams below. Supply systems with voltages Un
= 0-690 V AC (15-400 Hz) or 0-1000 V DC can be connected.
Measuring principle CM-IWS.2
A superimposed DC measuring signal is used for measure-
ment. From the superimposed DC measuring voltage and its
resultant current the value of the insulation resistance of the
system to be monitored is calculated.
Measuring principle CM-IWN.x, CM-IWS.1
A pulsating measuring signal is fed into the system to be
monitored and the insulation resistance is calculated. This
pulsating measuring signal alters its form depending on the
this altered form the change in the insulation resistance is
forecast. When the forecast insulation resistance corresponds
to the insulation resistance calculated in the next measure-
ment cycle and is smaller than the set threshold value, the
output relay de-energizes. This measuring princiiple is also
suitable for the detection of symmetrical insulation faults.