Data Sheet

QT20.241, QT20.241-C1

Q-Series

24V, 20A, THREE PHASE INPUT

Apr. 2017 / Rev. 2.1 DS-QT20.241-EN

22.11. BACK-FEEDING LOADS

Loads such as decelerating motors and inductors can feed voltage back to the power supply. This feature is also called

return voltage immunity or resistance against Back- E.M.F. (E

lectro Magnetic Force).

This power supply is resistant and does not show malfunctioning when a load feeds back voltage to the power supply.

It does not matter whether the power supply is on or off.

The maximum allowed feed-back-voltage is 34Vdc. The absorbing energy can be calculated according to the built-in

output capacitor which is specified in chapter 6.

22.12. USE IN A TIGHTLY SEALED ENCLOSURE

When the power supply is installed in a tightly sealed enclosure, the temperature inside the enclosure will be higher

than outside. In such situations, the inside temperature defines the ambient temperature for the power supply.

The following measurement results can be used as a reference to estimate the temperature rise inside the enclosure.

The power supply is placed in the middle of the box, no other heat producing items are inside the box

Enclosure: Rittal Typ IP66 Box PK 9519 100, plastic, 180x180x165mm

Load: 24V, 16A; (=80%) load is placed outside the box

Input: 3x 400Vac

Temperature inside enclosure: 55.9°C (in the middle of the right side of the power supply with a distance of 2cm)

Temperature outside enclosure: 24.9°C

Temperature rise: 31.0K

26/27

All parameters are typical values specified at 24V, 20A, 3x 400Vac, 50Hz, symmetrical mains voltages, 25°C ambient and after

a 5 minutes run-in time unless otherwise noted.