MC 255 Instruction Manual 4-MC255-01
©2014 Alarmtech Rev. MC255_1427en Page 2of 2
OPERATING PRINCIPLE
MC 255 magnetic contact has two parts: the contact part
with a reed switch and the magnet part. In its neutral
position the reed switch remains closed under the force of
the magnetic field. Opening the monitored object increases
the distance between the reed switch and the magnet. This
reduces the influence of the magnetic field on the reed
switch until it opens and activates an alarm.
Magnetic contacts should not be installed in the vicinity of
strong magnetic fields.
INSTALLATION
Detailed installation instructions can be found in MC 255
Installer Manual.
Contact and magnet should be aligned axially in the frames
and leaves of the monitored objects (windows, doors etc.).
Offset will reduce the working distances. The contact should
be mounted in the stationary part of the monitored object
(ex. door frame) and the magnet in the movable part (ex.
door leaf). Before mounting, holes must be drilled. The self-
cutting and self-locking thread of the housing enables easy
and reliable installation in ф10 mm holes in wood and
plastic.
The construction of the contact enables rotation during
mounting, thus protecting the cable from mechanical stress.
For sites where it is impossible to mount the contact
directly, a variety of accessories is available.
Accessories with a strong magnet provide a bigger working
distance for more demanding applications and maintain the
parameters of the magnetic contact when mounted in
ferromagnetic environment.
Only non-ferromagnetic screws may be used when mounting
the contact using accessories.
After the installation, use an ohmmeter to check the
electrical connections and test the function of the magnetic
contact.
Warning: applying excessive force to the housing of the
contact may damage the glass body of the reed switches
inside.
Warning: appropriate accessories must be used for
installation in ferromagnetic environment.
RESISTORS (OPTIONAL)
MC 255 is available in two additional options with resistors
of the chosen value: MC 255-R with one resistor parallel to
the alarm switch and MC 255-2R with two resistors in 2EOL
configuration
DISTANCE TABLE
X –not recommended
ORDERING INFORMATION
Magnetic contact with rotating cable, 2m cable
Magnetic contact with rotating cable, 6m cable
Magnetic contact with rotating cable, 10m cable
We reserve the right to changes without notice.We reserve the right to changes without notice.
