2
•
Before making any connections, check the
experiment leads for damaged insulation
and exposed wires.
•
Replace a faulty fuse only with one matching
the specifications stated at the rear of the
housing.
•
Disconnect the equipment from the mains
before replacing a fuse.
•
Never short the fuse or the fuse holder.
•
Never cover the air vents in the housing.
This is necessary in order to ensure suffi-
cient circulation of air required for cooling
the internal components of the equipment.
•
The equipment may only be
opened/repaired by qualified and trained
personnel.
2. Description
The 12 V/3 A AC/DC power supply is character-
ised by its high voltage stabililty, low residual
ripple and overload protection.
In the range from 0 to 12 V, it features one con-
tinuously regulated DC output and 4 constant
AC voltage outputs (3 V, 6 V, 9 V and 12 V).
An analog meter displays the DC voltage. The
voltage is floating and is tapped from the front
sockets. It is galvanically isolated from the AC
outputs.
The voltage outputs are safeguarded by semi-
conductor fuses (multifuses).
Only one AC output can be operated at a time.
Caution:
Connecting instruments with current outputs up
to 5 A DC in series can be done without any
difficulty. For instruments with current outputs
over 5 A, a diode needs to be connected in par-
allel with the output sockets of each instrument
for overload protection. The anode of this diode
is connected to “-“, and the cathode to “+”. The
diode has to be rated for the maximum load
current.
The AC/DC power supply 1002775 is for opera-
tion with a mains voltage of 115 V (±10%), and
the 1002776 unit is for operation with a mains
voltage of 230 V (±10%).
3. Technical data
DC output
Voltage:
0 to 12 V, continuously
variable
Stability 0 … 100% load:
≤
30 mV
Residual ripple:
≤
3 mV rms.
Current:
3 A, up to 5 A max. for
brief intervals
Cut-out current:
> 5 A
AC output
Voltage:
3, 6, 9, 12 V
Current: 3
A
Mains voltage:
See back of instru-
ment
Operating temperature: 0…40° C
Storage temperature:
-25…70° C
Display:
Analogue, class 2.5
Fuses:
T 1 A primary, 5 semi-
conductor fuses (multi-
fuses) secondary
Connections:
4-mm safety sockets
Dimensions: 230x115x190
mm³
approx.
Weight:
5 kg approx.
4. Operation
4.1 Outputting DC voltage
•
Set voltage adjustment knob to 0 (fully anti-
clockwise).
•
Connect instrument to mains.
•
Connect DC load to both output sockets
(blue = minus, red = plus). The chassis is
connected to the ground of the line input.
•
Flip power switch up (power light is illumi-
nated).
•
Select desired voltage with the voltage
regulator (which can be read on the voltage
display).
4.2 Outputting AC voltage
The AC range offers preset constant voltage
levels.
•
Connect instrument to line voltage.
•
Connect AC load to one of the AC outputs.
•
Flip power switch up (power light is illumi-
nated).
4.3 Changing fuses
•
Disconnect the instrument from the mains.
Pull out the the plug.
•
Use a screwdriver to open the fuse box at
the back of the instrument.
