99 Washington Street
Melrose, MA 02176
Phone 781-665-1400
Toll Free 1-800-517-8431
Visit us at www.TestEquipmentDepot.com
testo 755 · Current/voltage tester
Instruction manual
1 Contents
1 Contents
1 Contents ........................................................................ 2
2 Observe prior to use! ................................................... 3
3 Safety instructions ....................................................... 3
4 Intended use ................................................................. 3
5 Technical data .............................................................. 4
6 Overview ....................................................................... 6
6.1. Display and control elements ........................... 6
6.2. Explanation of icons ......................................... 7
7 Operating the instrument ............................................ 7
7.1. Switching the instrument on ............................. 7
7.2. Switching measuring point illumination on/off .. 7
7.3. Switching the instrument off ............................. 8
8 Carrying out a test ....................................................... 8
8.1. Preparing the test ............................................. 8
8.2. Voltage testing ................................................. 8
8.3. Single pole phase testing (only testo 755-2) .... 9
8.4. Current measurement ...................................... 9
8.5. Continuity/resistance testing ............................ 9
8.6. Rotating magnetic field direction detection
(only testo 755-2) .................................................... 9
9 Service and maintenance .......................................... 10
9.1. Replacing the batteries .................................. 10
9.2. Maintenance................................................... 10
9.3. Storage .......................................................... 10
9.4. Cleaning ......................................................... 10
10 Protecting the environment ..................................... 10
2
4 Intended use
2 Observe prior to use!
• The instruction manual contains information and instructions which are
necessary for operating and using the instrument safely. Before using
the instrument, read the instruction manual carefully and comply with
all aspects of it. Keep this document to hand so that you can refer to it
when necessary. Forward this documentation to any subsequent users
of the instrument.
• If the manual is not followed, or if you fail to observe the warnings and
instructions, there is a risk of fatal injury to the user and damage to the
instrument.
• Before using the fork meter in places with loud background noise,
make sure that the acoustic signal is discernible.
3 Safety instructions
• The instrument may only be used by trained personnel. During all
operations, please observe the Employers' Liability Insurance
Association provisions for health and safety at work.
• In order to prevent electric shock, take safety precautions when
working with voltages greater than 70 V (35 V) DC or 33 V (16 V)
rms. AC. These values are the limit for contact voltages in accordance
with DIN VDE (values in brackets apply to restricted areas, for example
agricultural sectors).
• The instrument may only be touched at the designated grip areas, the
display elements must not be covered.
• Maintenance work that is not described in this documentation must
only be carried out by trained service technicians.
• If the instrument is modified in any way, operational safety can no
longer be guaranteed.
• The fork meter must not be used while its battery compartment is open.
• Batteries must be checked before use and changed if necessary.
• If there is any battery leakage, the instrument must no longer be used
until it has been checked by our Customer Service.
• The battery acid (electrolyte) is highly alkaline and electrically
conductive. Risk of acid burn! If the battery acid comes into contact
with your skin or clothing, thoroughly rinse the areas affected
immediately with plenty of water. If battery acid gets into your eyes,
rinse them immediately with plenty of water and seek medical advice.
4 Intended use
The instrument may only be used under the conditions and for the purpose
for which it was designed:
• Current measurement, voltage testing in the AC/DC range of
6 to 600 V (testo 755-1) or 6 to 1000 V (testo 755-2), continuity testing /
resistance testing
• Only use the instrument within the specified measuring ranges of the
following overvoltage categories:
- Voltage measurement: CAT IV 600V, CAT III 1000 V
- Current measurement: CAT IV 300V, CAT III 600 V
The instrument must not be used for the following circumstances:
• In potentially explosive atmospheres: the instrument is not explosionproof!
• When there is rain or other precipitation: risk of electric shock!
3
5 Technical data
5 Technical data
Voltage testing
Figures correspond to +23 °C ± 5 °C at <80% rel. humidity. Temperature
coefficient: 0.15 x specified accuracy per 1 °C (<18 °C and >28 °C).
Feature Values
Voltage range testo 755-1: 6 - 600 V AC/DC
Resolution 0.1 V
Tolerance 6 to 49.9 V: ± (1.5% of the display value + 5
Frequency range DC voltage, 14 Hz – 400 Hz
Acoustic
signalling
Voltage detection Automatic
Polarity detection Automatic
Range detection Automatic
Internal load Approx. 3.5 W at 1000 V
Current Is < 3.5 mA at 1000 V
Operating time 30 s
Recovery time 240 s
Automatic power on > 6 V
Reading memory (HOLD) testo 755-1: 6 - 600 V AC/DC
Overload indicator testo 755-1: > = 630 V AC/DC, LC display
Measurement category CAT III 1000 V / CAT IV 600 V
testo 755-2: 6 - 1000 V AC/DC
digits)
50 to 600 V / 1000 V: ± (1.5% of the display
value + 3 digits)
50 V AC, 120 V DC
testo 755-2: 6 - 1000 V AC/DC
shows OL
testo 755-2: > = 1050 V AC/DC, LC display
shows OL
Single pole phase testing (only testo 755-2)
Feature Values
Voltage range >90 to 690 V ± 10% AC voltage to earth
Frequency range 50/60 Hz
Acoustic
signalling
LED display Warning symbol
Rotating magnetic field detection (only testo 755-2)
Feature Values
Voltage range 100 to 400 V ± 10% phase to earth/neutral
Frequency range 50/60 Hz
LC display L and R
Yes
4
5 Technical data
Current test
Feature Values
Voltage range Max. 200 A AC
Frequency range 40 to 70 Hz
Resolution 0.1 A ± (3% of the display value + 3 digits)
Automatic power on > 10 A
Overload indicator > = 220 A, LC display shows OL
Measurement category CAT III 600 V / CAT IV 300 V
Continuity testing
Feature Values
Area 0 to 30
Tolerances ± (1% of the display value + 5 digits)
Test current < 5 A
Acoustic signalling Yes
Overvoltage protection 1000 V AC/DC
Automatic power on < 100 k
Resistance testing
Feature Values
Area 30 to 100 k
Tolerances ± (1% of the display value + 5 digits)
Test current < 5 A
Overvoltage protection 1000 V AC/DC
Automatic power on < 100 k
General technical data
Feature Values
Operating ambient
temperature
Storage
ambient temperature
Humidity Max. 75% RH
Operating altitude Up to 2000 m
Level of contamination 2
Protection class IP 64
Power supply 2 x 1.5 V (AAA / IEC LR03)
Power consumption Approximately 60 mA
Battery life More than 10,000 measurements (< 5 s per
Dimensions (H x W x
D)
Weight Approx. 320 g
Safety standards EN 61243-3:2011, DIN VDE 0682-401:2011,
Authorisations TÜV GS, CE, CSA
-10°C to 50°C
-15°C to 60°C
measurement)
Approx. 199 x 62 x 40 mm
DIN EN 61010-1:2011
5
6 Overview
Feature Values
Warranty
Duration: 2 years
6 Overview
6.1. Display and control elements
1 Grip area
2 Switch on measuring point illumination and LC display illumination
3 HOLD (record reading)
4 LED safety extra-low voltage exceeded / Single pole phase testing
5 LC display
Display Meaning
AC AC voltage is applied
DC DC voltage is applied
HOLD Reading is recorded
V Voltage in V
A Current in A
• Safety
• Single pole phase testing (only testo 755-2):
extra-low voltage exceeded (> 50 V AC /
> 120 V DC)
phase detected
6
7 Operating the instrument
Display Meaning
Ω, kΩ Resistance in ohms or kilo-ohms
Continuity
,
,
6 Measuring point illumination, white LED
7 Fork meter for conductor up to 12.9 mm (0.5") in diameter
8 Sensor zone current measurement
9 On the rear: battery compartment and bracket for the probe tips
10 Probe tips, exchangeable (plug-in connection, adhere to polarity: see
printing on probe tips and sockets!)
11 Probe tip cable with sockets for probe tips
Rotating magnetic field direction left or right
Battery (full / empty)
6.2. Explanation of icons
Icon Meaning
ntion! Warning about a danger spot, refer to instruction
Atte
manual
Caution
! Dangerous voltage, risk of electric shock
Continuous double or
category II DIN EN 61140
Suitable for w
Conformity mark, verifies compliance with the valid EU
Directives: EMC Directive (2014/30/EU) with the EN 61326-1
standard, Low-Voltage Directive (2014/35/EU) with the
EN 61010-1 standard
Fulfils applicabl
The instrument co
(2012/19/EU)
reinforced insulation in accordance with
ork on live parts
e Australian provisions
mplies with the WEEE Directive
7 Operating the instrument
7.1. Switching the instrument on
> Connect both probe tips or press any button.
- The instrument is switched on, the LC display shows ---.
7.2. Switching measuring point illumination
on/off
> To switch on/off: briefly press the button.
7
8 Carrying out a test
The measuring point illumination switches off automatically after 2 minutes.
7.3. Switching the instrument off
Automatic
If there is no voltage being applied to the probe tips and no current or
continuity is detected, the instrument switches off automatically after 10
seconds.
Manual
Switch off instrument manually: press [HOLD] >2 s
8 Carrying out a test
8.1. Preparing the test
Prior to every test, please ensure that the instrument is in perfect condition:
• For example, keep an eye out for broken housing or leaking batteries.
• Always carry out a function test before using the voltage tester, see
below.
• Check that the instrument is functioning perfectly (for example at a
known voltage source) before and after every test.
• If the safety of the user cannot be guaranteed, the instrument must be
switched off and secured to prevent unintentional usage.
Carrying out a function test
> Press HOLD for approx. 2 s.
- Instrument carries out a self-test. All segments of the LC display and
the alarm, along with the measuring point and display illumination, are
activated for approx. 2 s.
Recording a reading
> A reading is displayed: press the HOLD key.
- A short acoustic signal is emitted and the LC display shows the
recorded reading.
> To delete the recorded value, press the HOLD button once again.
- A short acoustic signal is emitted.
The recorded value will automatically be deleted after approx. 10 seconds
once voltage is no longer being applied to the probe tips. This is indicated
by a short acoustic signal.
Voltages below 6 V AC/DC cannot be recorded, ---- is shown on the LC
display.
Removing/installing the probe tip protector/extension
The probe tip protector and extension can be removed/installed as required.
Attention: Use of the probe tip protector may be required depending on the
national regulations or provisions!
> Probe tip protector: push onto probe tips or pull off.
> Probe tip extension: screw onto probe tips or unscrew.
8.2. Voltage testing
> Connect both probe tips to the test object.
- The instrument switches on automatically at a voltage of approximately
6 V or above.
- The voltage is shown in the LC display.
- In the case of DC voltage, the polarity of the indicated voltage relates
to the voltage tester probe tip.
8
8 Carrying out a test
- When the safety extra-low voltage is reached or exceeded (50 V AC /
120 V DC), an acoustic signal is emitted, the red LED comes on and
is illuminated in the LC display.
8.3. Single pole phase testing (only testo 755-
2)
Single pole phase testing is possible as from AC voltages of approx. 90 V.
During single pole phase testing to determine external conductors, the
display function may be impaired, for example due to insulating personal
protective equipment or other insulators.
Single pole phase testing is not suitable for testing for absence of voltage.
Two-pole voltage testing is required for this.
> Connect a probe tip of the voltage tester to the test object.
- is illuminated to signify phase testing on the relevant conductor.
8.4. Current measurement
Strong interferences in the vicinity result in an unstable display and
measurement errors.
✓ No voltage must be applied to the probe tips, so that the instrument
switches to current measurement mode.
> Push the instrument's fork over the live conductor as far as the sensor
zone.
- The reading is shown in the LC display.
8.5. Continuity/resistance testing
✓ Disconnect the test circuit/object from the power supply.
✓ Conduct a two-pole voltage test on the test object to confirm the
absence of voltage.
> Connect both probe tips to the test object.
- For continuity up to approx. 30 , an acoustic signal is emitted, for
resistance up to approx. 100 k the acoustic alarm remains inactive.
- The instrument switches off automatically after 10 seconds if no
continuity/resistance is detected. As soon as continui ty/resistance is
detected, the instrument switches back on automatically.
8.6. Rotating magnetic field direction
detection (only testo 755-2)
The rotating magnetic field direction detector is always active, L or R may
be constantly illuminated, however rotary field direction can only be
determined in a three-phase system between the external conductors.
The instrument displays the voltage between two external conductors.
1. Connect the probe tip L1 (-) to the presumed phase L1 and the probe
tip L2 (+) to the presumed phase L2.
2. Completely cover the grip area with your hands!
- If R is constantly illuminated: “right” rotating magnetic field.
- If L is constantly illuminated: “left” rotating magnetic field.
Cross-check:
> Repeat the process with switched probe tips.
- The opposite result must be indicated.
9
10 Protecting the environment
9 Service and maintenance
9.1. Replacing the batteries
The batteries must be replaced when the battery icon is illuminated in the
LC display.
1. Fully disconnect the instrument from the measurement object.
2. Using a screwdriver, unscrew the two metal screws on the battery
compartment until the battery compartment cover can be removed. Do
not unscrew the screws completely.
3. Remove the spent batteries.
4. Insert new batteries, type AAA / IEC LR03 (1.5 V), ensuring correct
polarity.
5. Put the battery compartment cover back on and screw down.
9.2. Maintenance
When operated in accordance with the instruction manual, the instrument
does not require any particular maintenance.
If a malfunction occurs during operation, the ongoing measurement should
be stopped immediately. Send the instrument to Testo Service for checking.
9.3. Storage
Storage areas must be
> If the instrument is not in use for a significant period of time: remove
the batteries in order to prevent any danger or damage due to any
potential leaking of the batteries.
dry.
9.4. Cleaning
Prior to cleaning, the instrument must be disconnected from all measuring
circuits.
> Wipe the instrument with a damp cloth and a small amount of mild
household detergent.
Never use any harsh cleaning agents or solvents to clean the instrument!
After being cleaned, the instrument must not be used until it has completely
dried.
10 Protecting the environment
> Dispose of faulty rechargeable batteries/spent batterie s in accordance
with the valid legal specifications.
> At the end of its useful life, send the product to the separate collection
for electric and electronic devices (observe local regulations) or return
the product to Testo for disposal.
10
Test Equipment Depot - 800.517.8431
99 Washington Street,
Melrose, MA 02176
TestEquipmentDepot.com
0970 7550 en
03 V01.00
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