Motor derating: Any adverse operating conditions require that the motor performance be derated. These conditions include; ambient temperature above 40°C, motor mounting position, drive switching frequency or the drive being over sized for the motor. … The slip is what allows an induction motor to produce torque.
What is derating of induction motor?
Induction motors (asynchronous or squirrel-cage motors) behave differently than permanent magnet motors. … Due to the design of the motor, it operates at a rated speed less than the synchronous speed, by a difference known as the slip speed.
What is purpose of derating factors?
Derating factor is a factor applied to determine safe power dissipation capacity of a transistor (or any semiconductor device) at elevated temperature. For example consider a power transistor rate for 10 W when ambient temperature is upto 70 deg C and it has a derating factor of . 5 W/deg C.
What is meant by derating current?
The derating curve shows which currents may flow continuously and simultaneously via all possible connections when the component is subjected to various ambient temperatures below its upper limit temperature. The upper limit temperature of a component is the rated value determined by the materials used.
How is cable derating factor calculated?
Selection of cable – Case #2
- Current capacity of 95 Sq.mm cable is 200 Amp, Resistance = 0.41 Ω/Km and. Reactance = 0.074 mho/Km.
- Total derating current of 70 Sq.mm Cable = 200 · 0.93 = 187 Amp.
- Voltage drop of cable = (1.732 · 139 · (0.41 · 0.8 + 0.074 · 0.6) · 200 · 100) / (415 · 1 · 1000) = 2.2%
Is standard for cable derating factor?
IEC 60502 is an International Electrotechnical Commission standard, which gives current ratings for medium voltage cables. … Derating factors considered are the ambient temperature, depth of laying and soil thermal resistivity for buried cables, and the grouping of cables.
What is temperature derating factor?
A specification showing how a rating stated at a particular temperature is reduced at higher temperatures. NOTE 1 Derating is usually expressed graphically or in terms of derating factors (e.g., mA/°C or mW/°C).
What does derating mean in English?
: to lower the rated capability of (something, such as an electrical or mechanical apparatus) because of deterioration or inadequacy.
Which of the following are the derating factors?
- Max. Conductor Temperature:90°C.
- Ambient Ground Temperature:30° C.
- Ambient Air Temperature:40° C.
- Thermal resistivity of soil:150°C cm/W.
- Depth of laying. 3.3, 6.6 & 11 kV Cables:90 cm. 22 and 33 kV Cables:105 cm.
- Max. Conductor Temperature. for Short Circuit:250° C.