16
3. Electric components
3.1 Drive unit
The drive unit consists of a twin drive which combines two sepa-
rate drive units for the electrical adjustment of the back and leg
part. A switch-mode supply with rectifier is part of the external
motor system. This switch-mode supply converts the input vol-
tage of 110-240 V AC at 50-60 HZ at 70-180 W into a low voltage
of 29 V DC. With this non-hazardous low voltage the motors and
the hand control are operated. The cables are isolated twice and
the power plug disposes of a primary fuse.
The internal emergency lowering is carried out by a 9 V battery.
In addition a power adjustment takes care of a constant veloci-
ty. The safety demands therfore corresponds to the safety class
II and the moisture protection IPX4.
The maximum switch-on time is indicated on the bed (type
label). E.g. 10% (2 min. on/ 18 min. off) means that each elec-
tronic adjustment should only be done for 2 min in 18 min (over-
heat control).
In case that the maximum operation interval of two minutes is
exceeded, due to e.g. continuous operation of the hand control,
overheating of the actuators resulting in the immediate discon-
nection of the bed´s power supply through the thermal fuse. It
takes a cooling-down time of approx. one hour, until the power
supply is automatically switched on again.
3.2 Locking device for all functions
The standard hand control with its 6 buttons comes with an
integrated locking device enabling the nursing staff to lock all
functions of the hand control by means of a key.
3.3 Level adjustment drive
The adjustment of the lifting appliance is effected through one
or two integrated low-voltage direct current drives whose range
of adjustment depends upon an integrated end-switch. The
adjustment drive is connected with the control unit by means of
a spiral cable.
* Bock Hazard Note
The maximum switch-on
time should not be more
than 2 minutes. A subse-
quent break of 18 minutes
has to be observed.
9-V-block batery for emergency
lowering