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FOR
IMMEDIATE RELEASE:
CONTACT:
M. Shallow
KMParts.com
(941) 473-0073
(941) 473-0987
sales@kmparts.com
http://www.kmparts.com
The CMD Contactor Monitoring Device - A
World Innovation: Moeller Contactor Monitoring
Device Makes Redundant Contactor Designs a Thing of
the Past.
Wood Dale, IL, December 21, 2007 -
Plant sections in virtually all applications are
implemented nowadays with safety in mind.
Safety-oriented control sections are used for
disconnection in the event of a hazard such as an
open safety guard or when an Emergency-stop button
is actuated. A failure of these plant sections is
mostly unacceptable even in the event of an error.
Special precautionary measures therefore have to be
taken, such as the implementation of redundant
disconnection. A contactor functions as a typical
disconnection device in the event of a hazard.
However, contactors tend to weld towards the end of
their service life at the latest and so two
contactors are often connected in series. This is a
particularly expensive measure, especially with
large contactors. The CMD contactor monitoring
device makes this redundant contactor design a thing
of the past.
The CMD monitors the main contacts of a contactor
for welding. It compares the contactor control
voltage with the state of the main contactors and
indicates this reliably with a mirror contact (IEC
EN 60947-4-1 Ann. F). If the contactor coil is
de-energized and the contactor does not drop out,
the CMD trips the backup circuit-breaker,
motor-protective circuit-breaker or switch-disconnector
via an undervoltage release.
The CMD also monitors the functioning of the
internal relay using an additional auxiliary make
contact of the monitored contactor. For this the
auxiliary make and break contact is positively
driven. The break contact is designed as a mirror
contact.
To ensure the functional reliability of the entire
unit, consisting of contactor, circuit-breaker and
CMD, the CMD is only approved for use with specific
Moeller contactors as well as motor-protective
circuit-breakers/circuit-breakers/or switch-disconnectors.
CMD can be used for monitoring the welding of all
contactors DILM7 to DILH2000 of the Moeller
contactor range. All auxiliary break contacts of
these contactors are designed as mirror contacts and
can be used for monitoring tasks. The PKZ2
motor-protective circuit-breakers can be used as
backup motor-protective circuit-breakers /
circuit-breakers or switch-disconnectors when fitted
with a U-PKZ2 (18VDC) undervoltage release. This
also applies to NZM1 to NZM4 circuit-breakers or N1
to N4 switch-disconnectors with an NZM..-XUV
undervoltage release.
These kinds of combinations are used in Germany and
Europe for safety-oriented applications. Previously
the series connection of two contactors was
recommended for circuits of safety category 3 and 4.
Now one contactor and Moeller's CMD is enough. The
CMD contactor monitoring relay is used for
Emergency-stop applications in compliance with EN
60204-1. It can also be used in the US automotive
industry where solutions are required that can
reliably detect the welding of the motor starters
and safely disconnect the motor feeder. Further
applications are possible with crane applications
that still prefer bar-mounted contactors: In these
applications EN 60204-32 requires type 2
coordination for contactors. Moeller's vacuum
contactors can also be used with the CMD.
In addition to the CE mark, the CMD is approved by
the German trade association for use as a safety
module. As a world market device, it also has UL and
CSA approval for the North American market.
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