ABB ACH550-02-645A-4 [401/454] Derating

Technical data 397

ACH550-02 User’s Manual

Note 1: The ratings apply in ambient temperatures up to 40 °C

(104 °F).

Derating

The load capacity (current and power) decreases if the

installation site altitude exceeds 1000 m (3300 ft), or if the

ambient temperature exceeds 40 °C (104 °F).

Temperature derating

In the temperature range +40 °C…50 °C (+104 °F…122 °F), the

rated output current has to be decreased 1% for every 1 °C

(1.8 °F) above 40 °C (+104 °F). The output current is calculated

by multiplying the current given in the rating table by the derating

factor.

Example. If the ambient temperature is 50 °C (+122 °F), the

derating factor is 100% - 1%/°C = 90% or 0.90.

The output current is then 0.90 ·I

Altitude derating

In altitudes from 1000…4000 m (3300…13,200 ft) above sea

level, the derating is 1% for every 100 m (330 ft). If the

installation site is higher than 2000 m (6600 ft) above sea level,

please contact your local ABB distributor or office for further

information (see page 421).