Siemens SIMOTICS XP 1MB5 Operating Instructions Manual page 104

Operation
8.1 Safety instructions for operation
In an explosive atmosphere, there is a risk of an explosion. This can result in death, serious
injury or material damage.
• Install an interlock circuit that prevents the machine from being switched on if the separately
driven fan is not switched on/is not operational.
• Do not commission the machine without a separately driven fan.
• Always use PTC thermistor monitoring when operating force-ventilated machines with a
converter. Trip units according to Directive 2014/34/EU ("Explosion Protection Directive") or
according to country regulations are always necessary when using PTC thermistor
monitoring.
Explosion hazard due to overheating of the machine caused by a layer of dust
Deposits of dust have a thermal insulation effect, which can lead to the machine overheating.
The maximum surface temperature of the machine cannot be adhered to. The dust can ignite,
resulting in an explosion. This can result in death, serious injury or material damage.
• Dust the machine regularly.
• Do not allow dust layers thicker than 5 mm to build up on the machine surface.
• Do not switch the machine on until the dust has been removed.
Risk of explosion due to excessive bearing temperature
The surface temperature cannot be maintained within maximum permissible limits if the
bearing becomes too hot. The dust can ignite, resulting in an explosion. This can result in death,
serious injury or material damage.
• Monitor the bearing temperature (Page 96).
• In addition to the current-dependent overload protection system located in the three phases
of the connecting cable, we recommend that you also monitor the temperature rise in the
machine using temperature sensors integrated in the stator winding.
Explosion hazard if the bridging is removed from the insulated bearing
Removing the factory-fitted bridging of the insulated bearing leads to potential differences
between the rotor and the grounded motor. This can cause the generation of sparks, which
especially in an explosive atmosphere can ignite surrounding dust or combustible gases.
Explosions can occur. There is also a risk of an electric shock. Death, serious injury, or material
damage will result.
• Do not open the bridging of the bearing insulation during operation.
Explosion hazard from hybrid mixtures
Hybrid mixtures are mixtures of flammable dusts with explosive gas/air atmospheres which can
together create a dangerous explosive atmosphere if they occur at the same time. Changes can
arise in the safety performance characteristics here, such as a change in the zonal classification,
increase in the explosion pressure, reduction in the minimum ignition energy and a reduction in
the maximum temperatures to be complied with.
102
1MB5 shaft height 400/450
Operating Instructions, 04/2023, A5E52802354A