162 Technical data CG Drives & Automation 01-5980-01r2
13.3.2Derating at high altitude
The Emotron TSA softstarter can operate at an altitude up
to 1,000 m
(3280 ft)without derating.
Above 1,000 m
(3280 ft)the thinner air will have several
negative effects on the performance of the softstarter,
therefore a derating is done.
For elevations in excess of 1,000 m
(3280 ft), the derating of
the nominal current is 1% per 100 m (328 ft). The Emotron
TSA softstarter can be operated up to 4,000 m
(13123 ft), in
which case it can only be operated at 70% of the nominal
current it was originally constructed for.
Example:
A motor with the following data is going to be used at
2,100 m (6890 ft)altitude:
Voltage: 400 V
Current: 42 A (normal duty)
Power: 22 kW
Due to the high altitude the TSA model 52-042 will no
longer be adequate for the purpose.
The derating 1%/100 m
2%/°C (0.55%/ degree F) is
calculated for the altitude above the rated:
2,100 - 1,000 (6890 -
3280 ft)= 1,100 meters (3610 ft)
above rated altitude, that gives:
(1,100 m/100 m) x 1% = 11%
Hence the nominal current must be derated by 11%.
The next higher rated model, TSA52-056, rated for 56 A
nominal current, will be derated to:
56 A - (11% x 56 A) = 49.8 A, which is well above the
required 42 A, and therefore TSA52-056 could be selected
in this case.
NOTE: If the unit has an I/O board the maximum altitude
with derating is 2,000 m.
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