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Operating instructions CMVpro 125-400 ATEX | Version 1-en
• is a required protective device,
• shall be installed in an easily-accessible location near the fan,
• provides qualified personnel a means of directly controlling and disconnect-
ing the electrical power supply from the fan,
• shall therefore be executed as a lockable all-pole disconnect switch.
DANGER
Use only an explosion-proof isolation switch if the isolation switch
is installed in a potentially explosive area.
8.2.2
Motor protection switch installation
An electric motor with a nominal power rating over 0.5 kW is to be protected
against overload and connected to the electrical power supply with a motor pro-
tection device (overload and short circuit protection) suitable for this.
NOTICE
Risk of overheating of the electric motor
Damage to motor
The motor protection switch does not reliably protect the electric motor from
overheating, particularly with insufficient motor cooling due to low speed, defec-
tive fan impeller, or clogged ventilation grid.
u
The installation of a motor protection switch is the responsibility of the oper-
ator.
u
Specify the motor protection switch based on the motor rated current on the
nameplate.
If a frequency converter (FC) is used, clarify whether integrated motor protection
functions allow for fan operation without an additional motor protection switch.
The FC is to be parameterized with the motor data by qualified personnel.
8.2.3
PTC thermistor tripping device installation
Based on ATEX zone and FC operation, the electric motor of the fan is
equipped with thermal motor protection. There are 3 PTC sensors (PTC thermis-
tors) in the motor windings for temperature monitoring, with an additional termi-
nal in the terminal box.
The PTC sensors are to be connected to an ATEX-certified PTC thermistor trip-
ping device. Observe the following points when doing so:
• For the connection of the PTC thermistor tripping device, read the equip-
ment manual and the operating instructions of the electric motor.
• Feed the connection cable into the terminal box of the electric motor
through an Ex cable gland.
PTC thermistor tripping devices are usually not approved for use in potentially
explosive atmospheres and must be installed in a safe location (e.g., in a protec-
tive casing or in the FC control cabinet).
Connecting PTC thermistor tripping unit to FC
When connected to a FC, shutdown should be performed by the "safe stop"
safety function. This ensures that no residual voltage is applied to the motor
windings and that the electric motor can cool down as quickly as possible.