NUE046 L/O 2 jh 7/05 1

Learning outcome 2

Motor protection

NUE046 L/O 2 jh 7/05 2

Over temperature protection

If the temperature of the insulation is exceeded, it starts to degrade and will eventually fail.

NUE046 L/O 2 jh 7/05 3

The most common and effective protection is thermal overload devices.

NUE046 L/O 2 jh 7/05 4

Primary resistance starter

TOL device

NUE046 L/O 2 jh 7/05 5L/O 2.4

NUE046 L/O 2 jh 7/05 6L/O 2.4

NUE046 L/O 2 jh 7/05 7L/O 2.4

NUE046 L/O 2 jh 7/05 8

Typical TOL with adjustable settings.

Adjustable electronic protection device with overload, phase failure and asymmetry protection.

NUE046 L/O 2 jh 7/05 9Insulation damage due to overload in 2 phases.

NUE046 L/O 2 jh 7/05 10

Rotor damage due to locked rotor condition.

NUE046 L/O 2 jh 7/05 11

Common problems.

• Asymmetry – voltage and phases not correct

• Single phasing - loss of a phase• Overloading• Moisture• Foreign matter in motor –sand etc• Frequency fluctuation• Voltage fluctuation

P 240 section 10.10