Schneider Electric Altivar 12 Manual De Usuario

BBV28581  05/2010

93

Thermal protection by calculating the I

2

t.

• Naturally-cooled motors:

The tripping curves depend on the motor frequency.

• Force-cooled motors:

Only the 50 Hz tripping curve needs to be considered, regardless of the motor frequency.

Trip time in seconds

Motor current/ItH

The use of external overload protection is required under the following conditions:

• Repowering up the product since there is no motor thermal state memory.
• Running multiple motors
• Running motors rated at less than 0.2 times the nominal drive current
•

Using motor switching

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