Siemens SENTRON 3VL series, System Manual

Page: 78 / 360

Application planning
6.7 Use in harsh environments:
3VL molded-case circuit breakers
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System Manual, 03/2009, 110 0110 - 02 DS 01
6.7 Use in harsh environments:
If the SENTRON VL are to be used outside closed rooms or in harsh operating conditions,
the following information must be taken into account at the planning stage:
Derating factors under special ambient conditions
Harsh operating conditions include:
●
Altitude in excess of 2000 meters
● Temperature above/below 50 °C
● Frequencies outside the 50 / 60 Hz range
● Humidity
Use at altitudes above 2,000 meters
The lower air density at altitudes above 2,000 meters affects the key electrical data of
molded-case circuit breakers. The table in the Technical data (Page 159) shows the derating
factors that have to be taken into account when using the circuit breakers at altitudes above
2,000 m.
Use at different ambient temperatures
A reduction (derating) of the rated operational current of the SENTRON VL circuit breaker is
necessary if the ambient temperature exceeds 50 °C. The reference temperature is 40 °C for
circuit breakers with RCD modules or plug-in/withdrawable versions.
The permissible loads for various ambient temperatures in relation to the rated operational
current of the circuit breaker are shown in the technical data.
Furthermore, the following points must be taken into consideration, because each one of
these factors can influence the rated operational current and permissible load.
●
Type of circuit breaker (fixed-mounted, plug-in, or withdrawable version)
● Type of main connection (vertical/horizontal busbar, cable)
● Ambient temperature around the circuit breaker
● Altitude derating factors
● Temperature derating factors based on different trip units and connections
● Degree of protection