If the motor was outdoors or in a humid indoor environment then yes, absolutely.
Why? Well do you think IP 55 is going to keep humid air out of the motor? It won't, it won't even come close. Once the humidity is in there - which will happen - the last thing you need is it condensing out on live parts.
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If we learn from our mistakes I'm getting a great education!
moizpk2001,
The hot air inside the motor will expand and most likely will leak out through the seals, to balance the atmospheric pressure. When stops, the air will cool down, creating a vacuum inside the motor, absorbing moist air from the ambient (IP55 allows limited ingress, is not air tight). The moisture will condensate on metallic surfaces, producing a corrosive environment and also a conductive medium with obvious potential consequences. The heaters will automatically maintain an elevated internal temperature to prevent the condensation of the absorbed moisture. This particularly important for larger motors, where the consequences of failure could be very costly.
Cheers,
gr2vessels
