
9 Mains and environment
9.2 Ambient conditions
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Lenze · Drive Solution Designer · Manual · DMS 4.2 EN · 12/2013 · TD23
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Unearthed power systems
IT systems are power systems with an isolated neutral. They are used in the following countries and
industry sectors:
• In the public supply system in France and Belgium
•Chemical industry
•Mining
• Island power supplies (own generator)
•Hospitals
•Ship's mains
• Crane, conveyor, and hoist systems
• Paper and pulp industry
Advantages of the IT systems are the high fire and operator safety. Furthermore there is no discon-
nection during the first earth fault.
9.2 Ambient conditions
9.2.1 Max. ambient temperature, motor/gearbox
The permissible load capacity depends on the ambient temperature. The load capacity also depends
on whether a geared motor or a motor without a gearbox is used.
Tip!
If a geared motor is used, the derating starts from a temperature of 30 °C, in the case of a
motor without a gearbox it starts from 40 °C.
Depending on the site altitude, the following correction values k
ϑ
result for geared motors:
ϑ
opr
k
ϑ
≤ 1000 m ≤ 2000 m ≤ 3000 m ≤ 4000 m
20 °C 1.15 1.04 0.92 0.81
30 °C 1 0.9 0.8 0.70
40 °C 0.8 0.72 0.64 0.56
50 °C 0.6 0.54 0.48 0.42
60 °C 0.4 0.36 0.32 0.28
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