Maintenance
Explosion-protected machines
136 56100000002002, 01/2016
– IIA, IIB: Total paint coating thickness ≤ 2 mm
– IIC: Overall coating thickness ≤ 0.2 mm for motors of group II (gas)
● Limit the surface resistance of the paint used:
– Surface resistance ≤ 1 GΩ for motors of groups II and III (gas and dust)
● Charge transfer limit
– 60 nC for Group I or Group IIA devices
– 25 nC for Group IIB devices
– 10 nC for Group IIC devices
– 200 nC for Group III devices (values not valid for strongly charge generating
processes)
● Breakdown voltage ≤ 4 kV for explosion group III (gas and dust)
9.2.3 Warning when repainting
Risk of explosion as a result of processes with high levels of electrostatic charging
For paint finishes in explosion group III, the paint can be electrostatically charged as
a result of intensive dust turbulence or processes with high levels of electrostatic
charging. Electrostatic discharges can occur. Minimize the risk of electrostatic
charging by applying effective measures according to IEC 60079-32-1. This can
result in death, serious injury or material damage.
Note
Paint finishes for IIC are optionally available with
more than 200 µm coat thickness.
Paint finishes exceeding 200 µm are tested with respect to electrostatic charging.
Motors with a coating thickness exceeding 200 µm may only be painted over if the
conditions mentioned above are complied with.
Note
Pay particular attention to the relubrication intervals for rolling bearings that deviate
from the inspection intervals.
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