Product description
Ex p control unit
Motor Purge Controller
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01-37A2-7D0003_Operating instructions_MPC_20210923_0_en.docx
Rev. 0
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Product description
3.1
General
The type of protection Ex p, called “pressurised enclosure”, is based on the
measure that explosive gases present in a closed volume are flushed out and
then an overpressure is generated and maintained in relation to the surrounding
atmosphere. Due to the higher pressure inside the housing compared to the
atmosphere, explosive gases cannot penetrate the inside of the housing at any
time. This creates an explosion-free area in which electrical devices can be
installed and operated, which are not themselves explosion-proof.
The APEX
mpc
or SILAS
mpc
control units described in these operating instructions
operate using the “pressurised enclosure with compensation of leakage losses”
technology. In detail, this refers to the maintaining of an overpressure in a
housing by supplying purging gas in order to compensate for any leakage losses
that occur in the housing.
The housing must be purged with purge gas prior to starting up, so that the
explosive atmosphere (gas) that has penetrated during downtime does not
become a hazard. The amount depends on the flow rate determined during the
initial start-up.
Since a safe state in the housing is only achieved at the beginning of the
operating phase, the Ex p control unit and its system components must be
designed to be explosion-proof.
3.2
Ex p control unit APEX
mpc
/ SILAS
mpc
The APEX
mpc
or SILAS
mpc
control unit with its system
components is an automatically operating control for
monitoring, controlling and regulating pressurised motors in
the hazardous areas of zone 1/21 or zone 2/22.
The Ex p control units are suitable for all common
applications in the pressurised enclosure of electric motors.
Each system structure consists of an Ex p control unit
APEX
mpc
or SILAS
mpc
and the associated pressure monitor mpv. The APEX
mpc
or
SILAS
mpc
control unit is intended for installation onto the pressurised motor and
the associated mpv at the purge air outlet point.
3.3
Pressure monitor, mpv
The pressure monitor mpv has two functions within the Ex p
control unit. First, it serves as a pressure relief valve, which
opens when the internal pressure is too high and reduces the
excess pressure. Second, an orifice is integrated in the
pressure monitor, via which the differential pressure is measured by means of
the sensor function unit.
In connection with the motor purge controller, this must be installed separately
on the pressurised motor. Furthermore, measuring hoses must be connected
between the pressure monitor and the sensor function unit.
