Power conversion equipment must be de-rated above a certain altitude (usually 1000 meters). Equipment that depends on air for its insulating and cooling

medium has a higher temperature rise and a lower dielectric strength value when operated at altitudes higher than 1000 meters (3300 feet). Application

of the correct de-rating factors is necessary to prevent drive failure.

The effect of high altitudes may eventually result in thermal damage to the power semi-conductors and related components (reduced effectiveness of the

heat sinks) as well as lower dielectric withstand capabilities. High altitude de-rating is, therefore, an important consideration during the initial application

of the drive.

Figure A.3

is provided as a quick reference to aid in derating the drive above specified altitude.

Note: This derate applies only to the inverter. However, if the inverter is placed in a pressurized cabinet so that the internal pressure is maintained at the value of atmospheric pressure

at 3300 ft. then there is no need for derate. Example: Heatsink is exposed to the outside and is not under positive pressure in an enclosed cabinet with forced air cooling or an

air-conditioning system. In such a case, derating is required.

Motor Derating

Consult the motor manufacturer for the applicable altitude de-rating factor before applying the motor. As a general guideline, consult the NEMA standard

MG 1-14.04 (Operation of AC and DC Fractional- and Integral-HP Motors and Generators at Altitudes Above 3,300 feet (1000 meters). However, the

motor manufacturer's specific de-rating data is always preferable.

YASKAWA ELECTRIC SIEP C710606 18A YASKAWA AC Drive – V1000 Technical Manual (Preliminary)

Altitude Derating for Yaskawa Inverters (meters)

102

100

Altitude (meters)

Altitude Derating for Yaskawa Inverters (feet)

102

100

Altitude (feet)

Figure A.3 Altitude Derating for Yaskawa Drives