3B Scientific AC-DC Power Supply User Manual
3B SCIENTIFIC® PHYSICS
AC/DC Power Supply, 12 V, 3A (115 V, 50/60 Hz)
AC/DC Power Supply, 12 V, 3A (230 V, 50/60 Hz)
1002775 (115 V, 50/60 Hz)
1002776 (230 V, 50/60 Hz)
Instruction sheet
04/12 ALF
1. Safety instructions
The 12 V/3 A AC/DC power supply unit conforms to all safety regulations for electrical
measuring, control, monitoring and laboratory
equipment, as specified under DIN EN 61010,
Section 1, and the equipment has been designed to meet protection class I. It is intended
for operation in a dry environment, suitable for
the operation of electrical equipment and systems.
Safe operation of the equipment is guaranteed,
provided it is used correctly. However, there is
no guarantee of safety if the equipment is used
in an improper or careless manner.
If it may be assumed for any reason that nonhazardous operation will not be possible (e.g.
visible damage), the equipment should be
switched off immediately and secured against
any unintended use.
In schools and other educational institutions, the
operation of the AC/DC power supply unit must
be supervised by qualified personnel.
supply are not surge-proof if exposed to external
voltages of more than 100 V with respect to earth.
• When using the equipment in conjunction
• Before using the AC/DC power supply unit
• Before using the AC/DC power supply unit
• The instrument may only be connected to
1 On/off switch
2 DC voltage adjustment
knob
3 DC voltage display
4 DC output
5 AC constant voltage
outputs
6 Fuse box (back of appa-
ratus)
Caution: the low-voltage outputs of the power
with other power supplies, e.g. for operating
electron tubes, be careful that no voltages in
excess of 100 V with respect to earth are
present at the outputs.
for the first time, confirm that the specifications printed on the rear side of the housing
are compatible with the local mains voltage.
for the first time, check the housing and the
mains lead for any damage. In the event of
any malfunction/operational defect or visible
damage, switch off the unit immediately and
secure it against unintended use.
the mains via a socket that has an earth
connection.
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• 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 sufficient 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 characterised by its high voltage stabililty, low residual
ripple and overload protection.
In the range from 0 to 12 V, it features one continuously 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 semiconductor 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 parallel 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 operation 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.
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