When an electric motor arrives in the Gibbons workshop for rewind or repair – or we’re asked to provide a replacement – we’ll often be told that the motor has failed. However, it’s fair to say that, if properly maintained, an electric motor shouldn’t just “fail” – there’s always a reason and it’s rarely down to the manufacture of the equipment. So read on as we launch a resolute defence of the indispensable electric motor.
According to ABB, more than half of electric motor failures are due to bearing issues, with insufficient or excessive lubrication being a major culprit. It’s recommended that a motor is re-greased every 2,000 hours or at three-month intervals, but specific information will have been provided by the supplier or installer. There should be no excuses for deficient greasing, but in many cases motors are housed in hard-to-reach areas and as long as they’re fulfilling their purpose they’re forgotten about. But even where access is awkward and a motor is running seemingly well, neglecting the lubrication schedule puts it at risk of overheating and subsequent failure.
In some cases, a motor will be supplied with the bearings only half-full of lubrication, with instructions to top up prior to first use. Unfortunately, in many cases this is ignored in the user’s urgency to get their machinery running and the lack of grease puts the bearing at risk of failure.
If the end user is not informed about the quantity of lubrication to apply to the electric motor bearings then they may apply too much grease. The rotation of the shaft churns the excess grease which leads to energy losses and overheating. This can be avoided by opening release valves during re-lubrication to allow excess grease to escape.
Uneven stress placed upon bearings by misalignment between the motor shaft and the driven equipment is guaranteed to cause premature failure. During installation it’s vital to ensure accurate positioning, whether it’s achieved with a straight edge, dial indicators or laser alignment.
It’s not just bearings, though. Winding failure due to overheating (which melts the wire’s insulation and causes a short circuit) is completely avoidable, providing motors are driving a suitable load and housed in a well-ventilated area.
As you can see, there’s always an external factor at play when a motor fails, so next time give the humble electric motor a break!
We’re a proud supplier of a huge range of ABB electric motors, along with high-performance, energy-efficient Gibbons-brand models. For a thorough, well-informed electric motor repair, rewind or installation, call us on 01621 868138 or email info@gibbonsgroup.co.uk.
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