voltage tester ax-t903
International Safety Symbols
Warning of a potential danger, comply with instruction manual.
Caution! Dangerous voltage. Danger of electrical shock.
Double insulation
Reference. Please use utmost attention.
Do not exceed the maximum allowable input range of any function
Insulated personnel body protective equipment up to 690V.
In order to avoid electrical shock, the valid safety and VDE regulations regarding
excessive contact voltages must receive utmost attention, when working with
voltages exceeding 120V (60V) DC or 50V (25V) rms AC. The values in brackets are
valid forlimited ranges (as for example medicine and agriculture).
Prior to measurement ensure that the test leads and the test instrument are in
perfect condition
When using this instrument only the handles of the probes may be touched – do not
touch the probe tips.
This instrument may only be used within the ranges specified and within low voltage
systems up to 690V.
Prior to usage ensure perfect instrument function (e.g. on known voltage source).
The voltage testers may no longer be used if one or several functions fail or if no
functionality is indicated.
Do not use this instrument under damp conditions.
Perfect display I sonly guaranteed within a temperature range of -10°C up to +55°C,
at relative humidity question <85%.
If the operator’s safety cannot be guaranteed, the instrument must be removed
from service and protected against use.
The safety can no longer be insured if the instrument:
Shows obvious damage
does not carry out the desired measurements
has been stored for too long under unfavorable conditions
has been subjected to mechanical stress during transport.
All relevant statutory regulations must be adhered to when using this instrument.
Appropriate Usage
The instrument may only be used under those conditions and for those purposes for which it was
conceived. For this reason, in particular the safety references, the technical data including
environmental conditions and the usage in dry environments must be followed.
When modifying or changing the instrument, the operational safety is no longer ensured.
The instrument may only be opened by an authorized service technician, e.g. for repair.
LCD display
1999 counts (3 1/2 digit ) LCD display with bargraph &
Voltage range
6,12, 24, 50, 120, 230, 400, 690V AC/DC
DCV: +1.0% of reading +3 digit
ACV: +1.5% of reading +5 digit
690VAC Max. measuring current
approx. ≤3.0mA
690VDC Max. measuring current
approx. ≤2.5mA
Voltage detection:
Polarity detection:
full range
Range detection:
Response time:
Updates 2~3 / sec.
ACV Frequency range:
Internal impedance:
approx. ≤1MΩ
Operation time
LCD on:
>4. 5V AC/DC
Single-pole Phase Test:
Voltage range:
100…690V AC
ACV Frequency range:
Continuity Test
Resistance range:
Test current:
Overvoltage protection:
690V AC/DC
Rotary Field Indication
Voltage range (LEDs):
Frequency range:
Measurement principle:
double-pole and contact electrode
Self-check test
Operation time
5s<250V AC/DC, Is< = 0.2A(690V)/30s max.
Overvoltage protection:
3s<400V AC/690V DC
Power supply
2x1.5V “AAA” Batteries
Temperature range:
-10°C up to +55°C
max.85% relative humidity
Overvoltage class:
age Tester Description:
1. Handle test probe – (L1)
2. Instrument test probe + (L2)
3. measurement point illumination
4. 2000 Counts LCD display
5. LED for “ ! ” warning voltage mode display
6. LED for single-pole phase test
7. LED for continuity
8. AUTOTEST(self-check test)
9. Measurement point lighting Button
10. Battery case
Explanations of Symbols
The voltage tester shows the following symbols:
DC voltage
AC voltage
DC voltage negative potential (DC)
Phase display from 100 to 690V ~ 50/60Hz
when used as a „single-pole“ phase tester.
Continuity test symbol
Rotating field display clockwise
Rotating field display anticlockwise
Device for work to be performed with voltage present
Battery replacement symbol
Inserting/Changing the Batteries
The voltage tester is operated with two micro-batteries (type AAA, in the scope of delivery).
Proceed as follows to insert or change the batteries:
• Loosen the screw on the battery compartment lid (9) with a suitable screwdriver
and remove it.
• Insert two micro-batteries (AAA) into the battery compartment. Observe the
polarity information in the battery compartment. If possible, use alkaline
batteries.They guarantee a longer service life.
• Then, carefully close and screw down the battery compartment lid again.
“symbol lights up on the
The batteries need to be changed if the „Low Bat
LCD display or when the LCD display stays dark after contacting both test tips.
The voltage tester will show no reading if the batteries are flat. The device must not
be operated with flat batteries or without batteries.
To prevent damage to the device from leaking batteries, remove the batteries from the device if
you will not be using it for a longer period. For the same reason, we recommend that you remove
flat batteries immediately.
Function test / Self test:
• Test the voltage tester on a known source.
• Warning: To avoid electric shock, disconnect the test leads from any source of voltage before turn
on the self-check test function.
• The “!” LED will light on when there is a voltage over 50V, even if the battery is low or if the
battery has been removed.
• When press “Autotest” button, all the bargraph will must be light on, and LCD display “000” ,and
The continuity test’s LED (6) will light on, buzzer sound. This shows the tester self-test was done.
Measuring Point Lighting
The voltage tester has a battery-operated measuring point lamp. Press button (8) to switch this
lamp on. The lamp stays on
as long as this button is kept pressed. When the button is released, the lamp goes off.
Carrying out Measurements
The twin-pole voltage tester has two handles, a connecting cable and an LCD display. Always hold
the voltage tester in such a way that you get a vertical view of the display. Strong incidence of light
may have an adverse effect on the display. For DC measurements, test tip is the positive pole,
and the test tip is the negative pole.
Before each voltage measurement, check that the device is working properly by measuring a known
voltage source. If the tester’s LCD display remains blank, take the voltage tester out of operation.
A defective voltage tester must not be used. Do not operate the device with flat batteries or
without batteries. Observe the regulations regarding work with electrical systems.
The device can be used for the following types of measurement:
Voltage measurement with high internal impedance
Always hold the voltage tester by the handles designed for this purpose. Never touch the device
beyond the handle ends. Hold the two test tips onto the measuring points to be tested. The voltage
tester switches on automatically with voltages higher than 4.5V AC/DC. The voltage measured is
shown on the LCD display. If the measured voltage falls below 4.5 V AC/DC, the voltage tester
switches off automatically.The LCD display shows the voltage values numerically and in the form of
a bargraph. The type of voltage (alternating current = AC or direct voltage = DC) and the polarity
are also shown on the LCD display. In the event of negative DC voltage, the numeric voltage value is
preceded by „ - „. Positive DC voltage is shown without a positive sign preceding the value.
Thanks to the input impedance of approx. 1MΩ, it is possible to perform voltage tests with high
input impedances without time restrictions.
The voltage tester also indicates a rotating direction (L or R) with measurements on single-phase
mains (L1 against N). This is not a device malfunction.
Rotating field direction display
The voltage tester can show the direction of the rotating field with three-phase systems. Hold the
voltage tester by the handles and provided. Never touch the device beyond the handle ends. Hold
the two test tips onto the measuring points to be tested. Test tip corresponds to L1, and test tip
corresponds to L2. The applied voltage and the rotating field direction is shown on the LCD display
The rotating field symbols (D) show the corresponding rotating field direction (L = anticlockwise / R
= clockwise).
Continuity check
The voltage tester can also be used as a continuity tester. Always hold the voltage tester by the
handles designed for this purpose. Never touch the device beyond the handle ends. The continuity
tester switches itself on automatically when the test starts, and switches itself back off when the
test has been completed. Check for correct functioning before beginning the test. If you connect
the two test tips with each other, you should heap a beep, and the continuity LED should light up.
If this is not the case, replace the batteries as described under „Inserting/Changing the Batteries“.
The continuity tester indicates resistances of up to<300 kOhm.
Using the Voltage tester as a ” single-pole” phase tester
The Voltage tester can also be used as a „single-pole“ phase tester. Always hold the voltage tester
by the handles designed for this purpose (3 and 6). Never touch the device beyond the handle ends.
This “phase test” serves as a quick test only. Please check again for zero potential with the twinpole measuring method before you do any work on this circuit. Observe the regulations regarding
work with electrical systems.
Before beginning the test, check the condition of the batteries by connecting the two test tips with
each other.
Check for correct functioning at a known alternating voltage source. Contact test tip ”L2” with the
measuring point to be tested. In the event of the phase (alternating current between 100 and
690V), the lightening symbol LED lights up.
The „single-pole“ phase display can be adversely affected by unfavourable ambient conditions
(electrostatic fields, good insulation etc.). In all cases, conduct an additional, twin-pole voltage
Maintenance and Disposal
Check the technical safety of the voltage tester regularly. It can be assumed that risk-free
operation is no longer possible if:
• there is visible evidence that the device has been damaged
• the device has been stored under unfavorable conditions for a longer period of time
• the device has been subjected to heavy transport strain.
The outside of the device should be cleaned with a soft, damp cloth or brush only. Do not use
abrasive or chemical cleaning agents which could damage the housing or impair operation.
Never try to open the housing, apart from the battery compartment.
When the device has become unusable, dispose of it in accordance with the current statutory
Disposal of batteries and rechargeable batteries
You, as the end user, are required by law (Battery Ordinance) to return all used
batteries/rechargeable batteries. Disposing of them in the household waste is prohibited!
Batteries/rechargeable batteries containing hazardous substances are marked by the shown
symbols. These symbols also indicate that it is prohibited to dispose of them in the household
waste. The heavy metals concerned are: Cd = cadmium, Hg = mercury, Pb = lead. You can return
flat batteries/rechargeable batteries free of charge to the collection points in your community, our
branches or anywhere else where batteries are sold.
You thus fulfil your statutory obligations and help to protect the environment!
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