LD Didactic 531 902 User manual

03/16-W07-Sel
Instructions for Use 531 902
Demo Multimeter, active (531 902)
1 Description
The demo multimeter is an overload-protected electronic
pointer measuring instrument for DC currents and voltages,
sinusoidal alternating currents and voltages, and resistances
With its superior large scale panel and the function and
operating mode switches on the front and rear, it is particularly
well suited for demonstration experiments. The measured
values are displayed directly on six switchable scales in 1–3
gradation with the zero point left or on a scale with the zero
point in the centre.
The current measuring range is from 1 A to 30 A, the voltage
measuring range from 1 mV to 10 kV, and the resistance
measuring range from 1 kto 300 k. Using the current clamp
(531 901), the current measurement ranges can be extended
up to 300 A for direct current and 200 A for alternating current.
Using the high-voltage probe (531 93) the voltage measuring
ranges can be extended to 300 kV for DC voltages that are not
hazardous.
Safety Instructions
The demo multimeter complies with the safety conditions for
electrical measurement, control, and laboratory devices
outlined by DIN EN 61010 part 1 and is designed in
compliance with protection Class II. It is meant to be
operated in dry rooms suitable for the use of electrical
equipment and facilities.
To ensure the safety of the user and to protect the device,
the demo multimeter is equipped with an automatic socket
lock. It is coupled to the function switch and only unlocks the
sockets required for the selected function. It also blocks
switching to non-permitted functions when the test leads are
plugged in.
Safe operation of the demo multimeter is ensured if it is used
as intended. Safety is not ensured, however, if the demo
multimeter is handled incorrectly (e.g. overloaded beyond the
permissible maximum) or carelessly. If it can be assumed
that the device can no longer be operated safely, the device
should immediately be taken out of commission (e.g. if there
is visible damage to the device)
Before operating the demo multimeter, inspect the case,
controls, and indicators for damage. In the event of mal-
functions or visible damage, take the demo multimeter out
of operation and secure it against unintentional operation.
Do not measure hazardous voltages above 500 V that
cause electric shocks and measure currents above 2 mA
DC only at voltages up to 500 V.
There is contact hazard if, at voltages higher than safety
extra-low voltages, the following thresholds are exceeded:
2 mA direct current or 0.5 mA alternating current (RMS
value) for the current through a non-inductive resistance of
2 kor 45 As for the charge at voltages up to 15 kV, and
350 mJ for stored energy at voltages above 15 kV.
Safety extra-low voltages are voltages below 60 V DC or
30 V RMS.
Do not exceed the maximum voltage of 500 V between
any of the sockets and ground.
Only use measuring leads in perfect condition and use
safety connecting leads (500 600 and following) to meas-
ure voltages higher than safety extra-low voltages.
Do not carry out any adjustment, maintenance, or repair
work on the open device while it is connected to power, or
have such work carried out by a specialist who is familiar
with the dangers involved.

Instructions for Use 531 902 Page 2/6
1 Large display, with 7 scales
2 Scale selector
3 Function display
4 Function switch
5 Operating mode display
6 Operating mode switch (on/off)
7 Zero point adjuster
8 Safety sockets,
with automatic socket lock
9 Viewing window for scale
10 Trend display
11 Quick reference guide
12 Battery compartment
13 Carrying handle
2 Scope of supply
1 Demo multimeter,
incl. 3 D cells 1.5 V, type IEC R 20
2 Holder, for mounting in the demonstration
panel frame (301 300)
3 Technical specifications
System: Moving coil mechanism
(core magnet)
Accuracy: Class 1.5
(1.5% of full scale)
Position in use: Vertical
Waveform: Sine
Frequency range: 45–200 Hz
Large display (front):
Length of scale arc: 200 mm
Height of digits: 25 mm
Scales: 0 ... 1 / 0 ... 3 / 0 ... 10 / 0 ... 30
/ 0 ... 100 / 0 ... 300 / -10 ... 10
Scale division: Linear
Increments 105 increments (0 ... 1/10/100)
66 increments (0 ... 3/30/300)
42 increments (-10 ... 10)
Trend display (rear):
Scale sheet length: 80 mm
Height of digits: 2 mm
Scales: 0... 10 / 0 ... 3 / -10 ... 10
Scale division: Linear
Increments 21 increments (0 ... 10)
33 increments (0 ... 3)
22 increments (10 ... 10)
Insulation:
Insulation: Double or enhanced throughout
Max. permissible voltage
of all sockets against ground: 500 V
Voltage measurements:
Internal resistance: 100 kmeas. function mV
10 Mmeas. function V
1 Gmeas. function kV,
without probe
30 Gmeas. function kV,
with probe
Current measurements:
Voltage drop: 120 mV meas. function As,
mA
200 mV meas. function A
Power supply:
3 D cells
1.5 V, type IEC R 20
or
1.2 V, type IEC HR 20
Battery life: For 1.5 V, type IEC R 20
approx. 500 operating hours
For 1.2 V, type IEC HR 20
approx. 100 operating hours
Automatic shut-off: after 50–60 min
General data:
Case dimensions: approx. 39 cm x 34 cm x 23 cm
Weight: approx. 5 kg

Page 3/6 Instructions for Use 531 902
4 Explanation of Symbols
Danger zone
(Follow the
instructions for use)
Common ground
connection
AC current,
Voltage
Battery test
Moving coil
mechanism (core
magnet)
Ground symbol
DC current, voltage
EC conformity mark
Electronics in
measuring circuit
Double or enhanced
insulation throughout
Accuracy
Class 1.5
Current clamp
5 Operation
5.1 Switching on and off:
To switch on:
- Depending on the desired operating mode, turn operating
mode switch from the OFF position to either position or
.
To switch off:
- Turn operating mode switch to the OFF position
When switched off, the pointer will be in the OFF position
(mechanical left stop of the scale).
Automatic shut-off:
After approximately 50-60 minutes, the demo multimeter will
switch off automatically and the pointer will be in the OFF
position. If this position of the pointer is not due to a negative
voltage:
- Turn the operating mode switch to the OFF position and
then back again.
If the demo multimeter will not be used for an extended period
of time:
- Remove the batteries from the battery compartment.
5.2 Inserting the batteries / battery change:
- Disconnect the demo multimeter from the measuring circuit.
- Carefully use a lever to remove the cover of the battery
compartment, e.g. with a screwdriver.
- Remove old batteries and clean contacts if necessary.
- Insert new batteries, observing correct the polarity.
- Close the cover again.
5.3 Battery test:
- Disconnect the demo multimeter from the measuring circuit.
- Set the operating mode switch to battery test.
- Read off battery condition on the back of the pointer
instrument.

Instructions for Use 531 902 Page 4/6
5.4 Setting the zero point
- Disconnect the demo multimeter from the measuring circuit
and switch it on.
- Use a screwdriver, for example, to set the zero point of the
desired scale.
5.5 Mounting in demonstration panel frame
- Hook the holder into the demo multimeter and clamp it with
the carrying handle.
- Hang the demo multimeter with holder on the profile rail of
the demonstration panel frame (301 300).

Page 5/6 Instructions for Use 531 902
6 Measuring voltages
6.1 Voltage measurements up to 300 V:
- Use the function switch to select the mV or V measurement
function and then set up the wiring.
- Switch on the demo multimeter by setting the current type to
or .
- Use the scale wheel to select one of the scales 0 ... 1,
0 ... 3, 0 ... 10, 0 ... 30, 0 ... 100, 0 ... 300 or -10 ... 10.
6.2 Voltage measurements up to 10 kV:
- Use the function switch to select the kV measurement func-
tion and then set up the wiring.
- Switch on the demo multimeter by setting the current type to
or .
- Use the scale wheel to select one of the scales 0 ... 1,
0 ... 3, 0 ... 10 or -10 ... 10.
7 Measuring currents
7.1 Current measurements up to 300 mA:
- Use the function switch to select the μA or mA measuring
function and then set up the wiring.
- Switch on the demo multimeter by setting the current type to
or .
- Use the scale wheel to select one of the scales 0 ... 1,
0 ... 3, 0 ... 10, 0 ... 30, 0 ... 100, 0 ... 300 or -10 ... 10.
7.2 Current measurements up to 30 A:
- Use the function switch to select the A measurement func-
tion and then set up the wiring.
- Switch on the demo multimeter by setting the current type to
or .
- Use the scale wheel to select one of the scales 0 ... 1,
0 ... 3, 0 ... 10, 0 ... 30 or -10 ... 10.
Attention:
Do not load measuring ranges more than the permissible
maxima:
250 V (measuring function in mV)
400 V (measuring function in V)
Attention:
Measure currents above 2 mA only at voltages up to 500 V.
Do not load measuring ranges to over 20 A.
Attention:
Do not measure voltages above 500V that are hazardous to
the touch.
Do not load measuring ranges to over 15 kV.
Attention:
Measure currents above 2 mA only at voltages up to 500 V.
Do not load measuring ranges to over 30 A.

Instructions for Use 531 902 Page 6/6
by LD DIDACTIC GmbH · Leyboldstraße 1 · D-50354 Hürth · Tel: [phone] · Fax: [phone] · E-Mail: [email protected]
www.ld-didactic.com Subject to technical changes
8 Measuring resistances
- Use the function switch to select the kmeasuring function
and then connect the test leads.
- Switch on the demo multimeter by setting the operating type
to .
- Use the scale wheel to select one of the scales 0 ... 1,
0 ... 3, 0 ... 10, 0 ... 30, 0 ... 100 or -0 ... 300.
- Scan the resistance to be measured with the measuring
conductors.
9 Measuring DC voltages up to 300 kV
Also required:
1 high-voltage probe 531 93
- Use the function switch to select the kV measurement func-
tion and then connect the high-voltage probe.
- Switch on the demo multimeter by setting the operating type
to .
- Use the scale wheel to select one of the scales 0 ... 30,
0 ... 100 or -0 ... 300.
- Use the high-voltage probe to scan the live wire (see the
instructions for use of the high-voltage probe).
10 Measuring currents up to 300 A (200 A)
Also required:
1 current clamp 531 901
- Use the function switch to select the measurement
function and then connect the high-voltage probe.
- Switch on the demo multimeter by setting the current type to
or .
For currents up to 10 A:
- Switch the current clamp to 20 A and use the scale wheel to
select one of the scales 0 ... 1, 0 ... 3, 0 ... 10 or -10 ... 10.
- Grip the wire carrying the current with the current clamp and
switch on the supply voltage (see instructions for use for the
current clamp).
For currents up 300 A ( ) or 200 A ( ):
- Switch the current clamp to 200 A and use the scale wheel
to select one of the scales 0 ... 30, 0 ... 100 or -0 ... 300.
- Grip the wire carrying the current with the current clamp and
switch on the supply voltage (see instructions for use for the
current clamp).
Attention:
Do not measure voltages above 500V that are hazardous
to the touch.
Do not load measuring ranges to over 300 kV.
Accuracy: Class 5
Attention:
Measure currents above 2 mA only at voltages up to 500 V.
Do not load measuring ranges more than the permissible
maxima:
30 (20) A in position 20 of the current clamp
300 (200) A in position 200 of the current clamp