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Questions from Customers: Why do I need a Motor Starter?

Why do I need a Motor Starter on my Dry Pipe System Air Compressor?

In short, to prevent this from happening:

burnt motor 2

burnt motor

What you see here is a burnt motor on one of our LT Series lubricated tank mounted units. In this instance the air compressor was run with no oil, causing the pump to seize.

Being that the pressure switch is tied to the motor and the system never received enough air to tell the pressure switch to cut off the motor did its job and kept on trying to turn the seized pump. Obviously this is impossible and the electricity used to turn the shaft of the motor had nowhere to go so the motor became overheated and burnt.

A motor starter for overload protection is defined in NFPA 70 4.30.32(2) as a device that “shall be arranged so that the opening of the control circuit will result in the interruption of current to the motor.” In other words, a motor starter is to an air compressor what a power strip is to your computer. When there is a voltage spike the motor starter will stop it from getting to your air compressor and shutdown all power to the unit until the situation is addressed.

Now, if there had been a motor starter in line (as we recommend on all systems) in this instance there would have been a power surge a moment after the pump seized, power would have been shut off to the unit a system alarm would have sounded and the situation could be addressed properly and without further issue. As it stands here our customer will have to buy a replacement unit, all due to a simple mistake – a mistake that could have been found before it got to this stage if a motor starter had been put in line.

5 thoughts on “Questions from Customers: Why do I need a Motor Starter?

  1. let’s see…red wire, blue wire….that’s a 208/240V motor. Probably on a dedicated circuit, with it’s own circuit breaker. No additional overload protection required. circuit breaker should have tripped on overload, and an additional motor overload may not have done anything. Sounds like you should provide inline fuses on the unit if you fall into the sweet spot between what your locked rotor amps are and enough juice to trip the breaker in time before this happens…

  2. Thank you for your great guides. If we do well maintain, we’ll save money for buying a new one. but when it expired or broke, we should purchase on a new air compressor. Go through to read more buyer guides and tips/tricks to use an air compressor. Hope to see more guides in the future. Many thanks.

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