12
Project planning
Operation with reduced supply voltage
Operating Instructions – Compact Extra-Low Voltage Drives
84
12.5
Operation with reduced supply voltage
The nominal voltage of the compact extra-low voltage drives is
DC 48
V. The rated
data on the nameplate refers to this nominal voltage.
Operation with permanently reduced load supply voltage is possible under the follow-
ing conditions:
• The operating speed and the operating power are reduced compared to the rated
values on the nameplate.
•
The supply voltage must not fall below DC 18 V.
• For applications with regenerative operation, a suitable diode circuit must be im-
plemented to avoid an impermissible voltage rise at the supply source. The param-
eters of the brake chopper must be adjusted. Observe the information on regener-
ative operation.
• The
DC 24
V control voltage must be decoupled from the load voltage to prevent
interference and damage. Ideally, the
DC 24
V control voltage and the load voltage
are supplied from two separate energy sources. (e.g. two separate power supply
units).
12.5.1
Information on regenerative operation
CAUTION
Danger due to:
- Missing decoupling of control voltage and load voltage.
- Increase in the DC 24 V control voltage.
- EMC influence of load circuit.
Possible damage to property and malfunctions
• Use two separate energy sources for supplying the load voltage and the
DC 24
V
control voltage (e.g. two separate power supply units).
In regenerative operation (braking operation) of the drive, energy is fed into the
DC
supply circuit. This results in an increase in the supply voltage at the drive and at
the output of the load supply.
Switched-mode power supplies are equipped with output voltage monitoring. If the
output voltage that is present at the power supply unit exceeds the value of the
device-dependent switching threshold, this can lead to the voltage supply being
switched off or to damage and interference. Connected sensors or actuators may also
be affected by switch-off, damages or interferences.
You can install a diode in the load circuit to prevent a possible regenerative voltage
rise at the supply source. Install the diode in the supply cable as shown in the follow-
ing figure:
BN
BK
GND
U
DC48V
Compact
extra-low voltage drive
U
DC24V
31496640395
U
DC48V
Load voltage
U
DC24V
Control voltage
26718014/EN – 11/2020
