Datasheet

QT20.241, QT20.241-C1
Q-Series
24V, 20A, THREE PHASE INPUT
Oct. 2006 / Rev. 1.0 DS-QT20.241-EN
All parameters are specified at 24V, 20A, 3x400Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
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27.2. PEAK CURRENT CAPABILITY
Solenoids, contactors and pneumatic modules often have a steady state coil and a pick-up coil. The inrush current
demand of the pick-up coil is several times higher than the steady state current and usually exceeds the nominal
output current (including the Bonus Power
®
) The same situation applies, when starting a capacitive load.
Branch circuits are often protected with circuit breakers or fuses. In case of a short or an overload in the branch
circuit, the fuse needs a certain amount of over-current to trip or to blow. The peak current capability ensures the
safe operation of subsequent circuit breakers.
Assuming the input voltage is turned on before such an event, the built-in large sized output capacitors inside the
power supply can deliver extra current. Discharging this capacitor causes a voltage dip on the output. The following
two examples show typical voltage dips:
Fig. 27-3 Peak load 40A for 50ms, typ. Fig. 27-4 Peak load 80A for 5ms, typ.
20ms/DIV
Output
Voltage
Output
Current
24V
0A
40A
18V
2ms/DIV
Output
Voltage
Output
Current
24V
0A
80A
16.5V
Peak load 40A (resistive) for 50ms
Output voltage dips from 24V to 18V.
Peak load 80A (resistive) for 5ms
Output voltage dips from 24V to 16.5V.
Please note: The DC-OK relay triggers when the voltage dips more than 10% for longer than 1ms.
27.3. 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
large sized output capacitor which is specified in chapter 8.
27.4. CHARGING OF BATTERIES
The power supply can be used to charge lead-acid or maintenance free batteries. (Two 12V batteries in series)
Instructions for charging batteries:
a) Set output voltage (measured at the battery) very precisely to the end-of-charge voltage.
End-of-charge voltage 27.8V 27.5V 27.15V 26.8V
Battery temperature 10°C 20°C 30°C 40°C
b) Use a 25A circuit breaker (or blocking diode ) between the power supply and the battery.
c) Ensure that the output current of the power supply is below the allowed charging current of the battery.
d) Use only matched batteries when putting 12V types in series.
e) The return current to the power supply is typ. 16mA at 25Vdc when the power supply is switched off (except in
case a blocking diode is utilized).