Danfoss DEVItector II V2 User manual

Intelligent solutions
with lasting eect
Visit devi.com
User Guide
DEVItector™ II V2
Tracing and correcting faults
in electric heating cable systems

DEVItector™ II V2User Guide
BC421332622232en-0101012 | ©Danfoss | FEC | 2022.07
User Guide
DEVItector™ II V2
Tracing and correcting faults in electric heating cable systems
Table of Contents
1. WARNINGS ...............................................................................................3
2. About this guide ..........................................................................................4
3. How it works..............................................................................................4
4. The equipment ...........................................................................................5
High Voltage Unit .........................................................................................5
Tracer ....................................................................................................5
Packing list ...............................................................................................6
Unpacking................................................................................................6
Transportation............................................................................................6
5. User Interfaces............................................................................................7
High Voltage Unit (HVU) user Interface.....................................................................7
HVU safety markings ......................................................................................8
User Interface of Magnetic tracer on crutch ................................................................9
User interface of Magnetic tracer - Hand held ..............................................................9
Tracers safety .............................................................................................9
6. Menus of DEVItector™ II V2 .............................................................................. 10
7. Troubleshooting a heating system installation ...........................................................14
Diagnosing the installation..............................................................................14
Common types of electric heating cables ................................................................15
Fault symptoms......................................................................................... 16
Gallery of Heating Cable Faults ..........................................................................17
8. Burning and Tracing ....................................................................................20
Overload protection ....................................................................................20
Burning procedure......................................................................................21
Tracing procedure ......................................................................................22
Guidelines for tracing an area ...........................................................................23
Hard cases of tracing....................................................................................26
Correction of fault ......................................................................................26
9. Glossary ................................................................................................27
10.Ordering information ...................................................................................27
11.Data sheet.............................................................................................. 28
12.Warranty ...............................................................................................30
Appendix A. ............................................................................................31

DEVItector™ II V2User Guide
BC421332622232en-010101 2022.07 | FEC | ©Danfoss | 3
1. WARNINGS
General Precautions
When not in operation detach the power cable from the mains supply.
Also, remove the safety key from the front panel.
The precautions also apply before leaving the High Voltage Unit unattended.
Before usage User Guide must be read and e-Learning must be completed!
ELECTRICAL HAZARD
10 kV~ / 400 V⎓
The DEVItector™ II V2 is a high voltage unit outputs
up to 10000 V~/ 400 V⎓!
This equipment must only be used by authorised
and instructed personal!
Do NOT leave the unit unattended!
Incorrect use can be fatal!
Besides the operator, all other persons must be kept
out of the working range. This also includes animals.
Preferably, the working range is marked by visible
markers, i.e. yellow tape.
Unplug all other equipment from the wall outlets to
disarm the risk of the high voltage cable terminals
touching a wire within the thermostat wall box.
When the burning is activated, DO NOT touch the high
voltage cables as neither the RCD relay or the high
voltage unit will disconnect in case of a faulty current.
The user must be aware that, if the equipment is
used in a manner not specied by the manufacturer,
the protection provided by the equipment may be
impaired.
Warning against operation when wet or in wet
conditions.
IP class of each part of DEVItector™ ll V2 is 20.
IP First number – protection against solid objects,
2 – protected against solid objects up to 12 mm, e.g.
person ngers. IP Second number – protection
against liquids, 0 – no protection.
WARNING
17 kg
Take special care considering heavy weight.
ELECTROMAGNETIC HAZARD
The High Voltage Unit can cause radio noise or
electromagnetic radiation, so pay attention to time
and place and inform people nearby!
Take special care when working at or near
hospitals to avoid disturbing medical equipment.
DEVItector™ should not be operated by people
with pacemaker or weak heart.
FIRE HAZARD
If the heating cables are not completely covered by
non-ammable materials such as sand or concrete,
and close to ammable material, cable burning
procedure should be undertaken with great
caution as the heating cable will burst into open
ames at the fault location.
Danfoss A/S doesn’t take responsibility for burned
property.
RESTRICTION OF USE
The equipment must only be used on electrical
heating cables while these cables and their
accessories are disconnected from the mains
supply and from building installation.
The user must be aware that, if the equipment is
used in a manner not specied by manufacturer,
the protection provided by the equipment may be
impaired.

DEVItector™ II V2User Guide
BC421332622232en-0101014 | ©Danfoss | FEC | 2022.07
2. About this guide
This DEVItector™ II V2 guide includes information about
tracing and correcting faults in electric heating cables.
The equipment and this guide are intended solely for
personnel working in the interest of Danfoss A/S. No
part of the equipment is to be resold or handed over
to other parties.
The equipment has been tested by Intertek
according to EN/IEC 61010-1 with amendments,
EN/IEC 61010-2-030 with amendments and
EN/IEC 61326-1 with amendments to protect you.
You are obligated to read this instruction carefully.
You are dealing with a potentially dangerous piece of
equipment. You are responsible for keeping yourself
and other persons and property safe.
WARNING: Any kind of equipment must be used
by instructed personnel. Any user must sign page
Declaration on Safety Rules (see Appendix A) to conrm
that he/she fully understands this Guide, all instructions
and the safety precautions necessary for operating the
DEVItector™ II V2.
3. How it works
Troubleshooting with DEVItector™ II V2 is a structured
technique for tracing and correcting faults in electric
heating cable systems.
The DEVItector™ II V2 comprises troubleshooting
equipment and this guide.
The DEVItector™ II V2 ensures an ecient and easy
tracing of heating cable faults.
The system features:
• Automatic test and measurement of electric heating
cables.
• Provoking faults in order to speed up the
troubleshooting process.
• Tracing hidden heating cables.
• Locating a fault within a few centimeters.
An installed and faulty heating cable is shown on Fig. 1.
It is most likely that you do not know the layout of the
heating cable as it is embedded in concrete or covered
by wood. Instead you will use a magnetic sensor to
‘see’ through the oor.
To locate the fault, you will have to create a magnetic
eld along the heating cable. You do this by sending
current through the cable. The trick is to create this
eld only between the cold cable and the fault. Then
the magnetic eld changes abruptly at the fault.
If the fault is a short circuit, you already have a return
path for the current. If the fault is a disruption, you
will have to make a short circuit without knowing the
location of the fault.
This is done by high voltage burning, in which the
polymer insulation between any two conductors
is converted into carbon, which is electrically
conductive.
A high voltage will burn through the weakest point
of the insulation which is at a fault. In case of several
faults, they are treated one after another.
Fig. 1: Heating cable embedded in concrete
and invisible to the eye is made visible to the
DEVItector™ II V2 tracing equipment. After burning
a carbon bridge at the fault, the magnetic eld to be
traced will appear only between the cold cable and
the fault.
Fig. 2: Sketch of magnetic ux of two conductors
carrying current in opposite directions. The magnitude
B of the ux is proportional to the current I and
decreases with distance r to the conductor. The ux of
the two conductors nearly cancels out. Note that the
screen may act as one of the conductors.

DEVItector™ II V2User Guide
BC421332622232en-010101 2022.07 | FEC | ©Danfoss | 5
4. The equipment
The DEVItector™ II V2 equipment comprises:
1. A high voltage unit (HVU) with a built-in 1,8 kHz
transmitter.
2. A battery-driven Magnetic tracer on crutch.
3. A battery-driven Magnetic tracer - Hand held.
The devices are shown in Fig. 3.
High Voltage Unit
The high voltage unit is used for creating a short
circuit at the fault location by applying a high voltage
between two conductors thus burning the polymer
insulation into a so called carbon bridge at the fault
location.
The HVU also acts as a transmitter exposing the
heating cable to a 1,8 kHz square voltage. This signal
generates a magnetic eld around the conductors
from the burner terminals along the cable to the fault
location.
Tracer
The tracer is a magnetic sensor which is an open
transformer comprising a ferromagnetic yoke and
a pickup coil. Thus the 1,8 kHz magnetic ux from
the heating cable is converted into an amplitude
modulated voltage. This signal is also converted into
an acoustical signal and output to a set of earphones.
A maximum tracer signal indicates the closest
distance to a cable segment. However, this case may
be modied due to the eect of closely neighboring
cable segments. The tracer has a gain and volume
control which allows you to adjust the meter or
volume level to t the actual depth of the cable.
Fig. 3: Photo of High Voltage Unit (left), the Magnetic tracer on crutch (mid) and the Magnetic tracer -
Hand held (right).
Note: The photos are not to scale.

DEVItector™ II V2User Guide
BC421332622232en-0101016 | ©Danfoss | FEC | 2022.07
Packing list
The DEVItector™ II V2 set comprises:
1. One High Voltage Unit (HVU) in transportation
cardboard box with shock absorbing foam.
2. One Magnetic Tracer, one Magnetic tracer - Hand
held and one earphone headset to be connected
to the tracer outlet placed in second transportation
cardboard box with shock absorbing foam.
Note: Keep transportation boxes for shipping in case
of repair which must be performed by manufacturer
(Danfoss A/S).
Enclosed in the top bag attached to the HVU you will nd:
3. Supply cord for single phase grounded main
supply according to EN/IEC 60799: Appliance
couplers and cord sets.
Two types are supplied, a type conformant to Danish
standards and a type conforming to German standards
(Schuco type).
Note: The main supply cord and main plug must
comply with national regulations.
4. Two identical mechanical keys to lock / unlock
the mains supply within the HVU.
5. Two yellow high voltage outlet cables attached
to the HVU within the top bag. The cables are tied
together to minimize radio noise emission.
6. This User Guide.
Unpacking
The equipment should be kept above condensation
temperature of the ambient air. If the equipment has
been stored at a lower temperature and then brought
into a warmer air, it must be acclimatized before use.
Transportation
The transportation cardboard box should be used for
transportation to prevent damage from dropping. In
particular transportation by air or ship will require a
high mechanical shock protection.
Avoid any conducting material like moisture, metal
or carbon powder to enter the equipment. Likewise,
avoid any spillage of liquids over the equipment.

DEVItector™ II V2User Guide
BC421332622232en-010101 2022.07 | FEC | ©Danfoss | 7
5. User Interfaces
High Voltage Unit (HVU) user Interface
This chapter explains how to handle the equipment and how to take safety precautions. The actual usage of the
equipment is explained in the chapter“Troubleshooting of the heating installation”.
Fig. 4: Front panel of High Voltage Unit. The encircled controls are explained below.
1. Mains connector:
Male connector with ground for mains
supply 220–230 V~ of 50–60 Hz according to
EN/IEC 60320-1.
2. Power ON/OFF switch:
A backlit button to turn ON/OFF the mains supply.
Also, the Safety Key must be engaged to operate
the HVU.
3. Safety Key Lock:
Must be engaged to enable the mains supply.
Insert key (not shown) and turn right 90° to activate
the mains supply.
4. Safety Button:
Must be engaged (pressed down) continously
during burning operation. Releasing the button
will switch OFF the high voltage output.
5. Display:
Used to show the control menu and actual values
of voltage, current and pulse cycle.
6. Menu Control knob:
The knob has two functions:
• turn it right or left to select menu items on the
display, or to change the value of a voltage , etc.;
• press it down to activate or toggle the selected
menu item.
7. Serial no. is located below the Safety Key Lock.

DEVItector™ II V2User Guide
BC421332622232en-0101018 | ©Danfoss | FEC | 2022.07
High voltage Outlet Cables
The heating cable is connected to the HVU by two High voltage Cables located in the top bag of the unit. The
cables are permanently connected to the unit. The ends are terminated by insulated alligator clips for ease of
connection to the heating cable.
Warning. Probe wires should be inspected before
use: the outer sheath and clamps sleeves should be
checked for possible damage. In case of any damage
the device must not be used.
Warning. Probes and wires are not to be repaired
or modied. In case of need of repair please contact
Danfoss A/S.
HVU safety markings
Front panel of the HVU
The HVU features several safety markings. Below you
will for each marking nd an image and a description.
Fig. 5: The equipment must only be used on electric
heating cables while these cables and their accessories
are disconnected from the mains supply or from
building installation.
WARNING
Hazardous live voltage on terminals.
Keep hands away from terminals
and connected cable.
Fig. 6: Located on front display besides the safety
button. The terminals are the alligator clips at the
end of the two High voltage Outlet Cables connected
through the top side of the HVU.
10 kV~ / 400 V⎓
Fig. 7: High Voltage label located on the front display.
The label signies potentially dangerous levels of
electrical energy.
Fig. 8 Electromagnetic hazard label located on the
front panel. The label signies that the High Voltage
Unit can cause radio noise or electromagnetic
radiation.
Fig. 9 Fire hazard label located on the front panel. The
label signies that cable burning procedure should be
undertaken with great caution as the heating cable
will burst into open ames at the fault location.
17 kg
Fig. 10 Heavy product label located on the front
panel. The label signies that the device is heavy and
needs special care.

DEVItector™ II V2User Guide
BC421332622232en-010101 2022.07 | FEC | ©Danfoss | 9
Inside the HVU cabinet
Fig. 11: Protective earth logo located on the inside of
the HVU close to the common ground.
High voltage Outlet Cables
HIGH VOLTAGE
10 kV~ / 400 V⎓
Fig. 12: High voltage Outlet Cables marking.
User Interface of Magnetic tracer on crutch
Fig. 13: Control panel of the large Magnetic tracer on
crutch unit.
Control items are explained below.
Gain:
Controls the amplication of the sensor signal as
shown on the meter. Turn clockwise to increase, and
counterclockwise to decrease amplication.
Oset:
The regulator “zero balance”allows in some cases to
compensate for induction of a signal reected by the
pointer indicator.
Volume:
Controls the acoustic amplication of the
sensor signal. Turn clockwise to increase, and
counterclockwise to decrease amplication.
User interface of Magnetic tracer - Hand held
Gain:
Controls the amplication of the sensor signal as
shown on the meter. Turn clockwise to increase, and
counterclockwise to decrease amplication.
Fig. 14: Control panel of the small Magnetic tracer - Hand
held unit.
Tracers safety
Both Tracer units are battery powered and contains
only safe voltage. Can only be used together with
DEVItector™ burner unit while in trace mode.

DEVItector™ II V2User Guide
BC421332622232en-01010110 | ©Danfoss | FEC | 2022.07
6. Menus of DEVItector™ II V2
Below is shown the display readout for the entire menu structure of the HVU. How to navigate is explained on
the pages below.
Fig. 15: Start Menu displayed during initialization after power on. After initialization, the Main Menu is displayed.
The menu has no user interaction. The item“V1.00”indicates the software version of the HVU.
Fig. 16: Main Menu: You can select among three modes: Burn, Trace and Setup. Each of those has their own
submenu as shown below.

DEVItector™ II V2User Guide
BC421332622232en-010101 2022.07 | FEC | ©Danfoss | 11
Safety Button on/pressed
Fig. 17: Burn Menu: The arrow indicates the active menu item as you turn the knob. On the display, the active
menu item is highlighted (the arrow is not shown on the display). The character“#”indicates a digit, e.g. “#.##A”
representing“1.23A”. Please note that the Burn Run display depends on whether you press the Safety Button or not.
Safety Button on/pressed
Fig. 18: Trace Menu: The“TRACE RUN”displays the Voltage and current of the signal.
Safety Button on/pressed
Fig. 19: Setup Menu: Here you select the Autostop current at which the burning operation is halted.

DEVItector™ II V2User Guide
BC421332622232en-01010112 | ©Danfoss | FEC | 2022.07
Fig. 20: Error Tests: During operation the HVU continuously tests itself. If one of the tests fails, one of the above
error messages will be displayed.
Navigating the menus
The DEVItector™ II V2 has four menu displays as shown
above. Each menu display features a number of menu
items.
• Selecting a menu item: Turn the knob until the
menu item ashes.
• Activating or deactivating a menu item: Press the
knob once.
• Changing the value of a menu item:
• Numbers: A number is composed of one or more
digits. Each digits is set in turn until all digits have
been entered.
The background of the active digit will ash. Turn
the knob clockwise to increase the value of the
digit, turn the knob counterclockwise to decrease
its value. Press the knob to enter its value and
continue to the next digit.
• ON/OFF values: Press the knob once.
Power on:
1. Turn the power on safety key in clockwise direction
to enable the power supply.
2. Press the backlit red button to activate the power
supply.
3. The power on menu will appear in the display.
4. From the power on menu, press the knob/dial
once.
5. The main menu will appear in the display.
Start Menu
After power on, the controller software initializes itself
and reports the progress in the display.
After initialization the Main Menu is displayed.
Main Menu
Here you select the operating mode among Burn,
Trace and Setup.
Burn menu
1. From the main menu, select menu “Burn”.
2. Press the knob once to enter the burning menu.
3. The Burn menu will appear in the display. High
Voltage and DC voltage will be activated by default.
4. Burning:
a. HV and DC must be activated. Select menu item
“Burn” and press the knob once. To activate the
burning, you need to press the Safety Button for
the desired duration of the burning process.
b. To stop the burning process, release the Safety
Button, press the knob once again or switch OFF
the power using the red button or the safety key.
c. Adjust the DC voltage by turning the knob.
A low DC voltage may cause a slow burning
process.
A high DC voltage may cause a poor carbon
bridge to appear due to violent burning. This will
make it dicult or impossible to trace the fault.
The conductivity of the carbon bridge must be
several times larger than the heating conductors
in order to short circuit the remainder of the
heating cable.

DEVItector™ II V2User Guide
BC421332622232en-010101 2022.07 | FEC | ©Danfoss | 13
Trace menu
1. From the main menu, turn the knob to select menu
item “Trace”
2. Press the knob once to enter the tracing menu.
3. Select a proper value of the tracing voltage.
Setup menu
1. From the main menu, turn the knob to select menu
item “Setup”.
2. Press the knob once to enter the setup menu.
3. Turn knob to set the Autostop Current to the
desired value, e.g. 1,00 Ampere.

DEVItector™ II V2User Guide
BC421332622232en-01010114 | ©Danfoss | FEC | 2022.07
7. Troubleshooting a heating system installation
Troubleshooting a heating system involves a diagnosis of
1. Power supply
2. Controller (thermostat) and sensors
3. Heating element(s)/heating cable(s) followed by a correction of the fault.
Diagnosing the installation
Note: You must follow this guide to ensure a safe and
optimal troubleshooting.
Warning. Conductive building materials, e.g. metal
mesh in concrete, metal water pipe, drain pipe, etc.,
might be in contact with cable under test. These
building materials or other metal parts might be not
grounded and, in this way, be dangerous during the
testing process.
1. Make sure that the circuit breakers, the optional
Residual Current Device (RCD) and the mains
voltage all are working properly and have correct
size/ value.
Do not proceed until this is the case.
2. Test the controller/thermostat:
Does it activate/deactivate, when the temperature
setting is changed?
If Yes go to step 5.
3. Check the external temperature sensor.
The resistance value [kOhm] for sensors may be
found in the installation instructions or in the
product catalogue.
If the sensor is faulty, replace it and continue with
step 5.
4. Repair or replace the controller/thermostat.
5. Check the output of the controller/thermostat.
If it is missing, continue with step 4.
6. If no faults appeared in the above tests, the
heating element/heating cable is probably faulty.
If a mistake occurs, check the heating element/
cable before proceeding.
7. Disconnect the thermostat from the heating
element/cable before starting the measurement of
the resistances.
Note: De-energize all power circuits before the
disconnecting.
8. Measure the resistance of the heating element/
cable using an ohm-meter. Resistance values of
heating element/cable may be found in the Data
Sheet, Product Catalogue, etc.
Compare the measured resistance of the heating
element/cable to the resistance of a representative
heating element.
If the two values dier signicantly, you probably
have a faulty heating element/cable.
9. Measure the insulation resistance of the heating
element/cable using an megohmmeter. The
insulation resistance should read >20 MOhm after
one minute at min. 500 V, preferably 2,5 kV.
If the insulation resistance value is lower than
20 MOhm, you probably have a faulty heating
element/cable.
Note: Real insulation resistance of heating
cables is usually more than 100 MOhm or even
1000 MOhm, and depends from cable length,
cable age, moisture conditions, etc.
10. A heating cable fault has now been veried and
you may start the troubleshooting process.

DEVItector™ II V2User Guide
BC421332622232en-010101 2022.07 | FEC | ©Danfoss | 15
Common types of electric heating cables
Before you start measuring the cable, it is important to know the dierent types of faults, and how they aect
the diagnosis. The 4 most common cable types are shown below. They feature from one to three conductors,
including the optional screen. Heating cables having more than three conductors are treated similar to twin
conductor cables.
Note: Only heating cables with two or more conductors can be handled by the DEVItector™. The tracing prin-
ciple is based on an electrical return path within the heating cable. So, keep in mind that “Single conductor
without screen”cable is not possible to be handled by the DEVItector™.
Single conductor without screen
Single conductor with screen
Twin conductor without screen
Twin conductor with screen
Connection coupling: End coupling:Cold cable: Heating cable: Screen:
Fig. 21: Four types of heating cable. The rst two cables are single conductor cables, and the last two are twin
conductor cables. Drawings indicates heating conductors as“heating cable”.

DEVItector™ II V2User Guide
BC421332622232en-01010116 | ©Danfoss | FEC | 2022.07
Fault symptoms
The types of faults comprise:
• One or more of the conductors disrupted (open circuit).
• Short circuit between two or more conductors.
• Combination of disruptions and short circuit.
The table below show the symptoms for a given combination of heating cable and type of fault.
Cable
Fault
Disruption of Short circuit between
Screen Conductor
(L or N)
Screen and
Conductor
Conductors
(L and N)
Single conductor
with screen
Will not show No heat
Fault no. 1
RCD-relay cut o
or fuse is burnt out
Fault no. 3
Twin conductor
without screen
No heat
Fault no. 2
Fuse is burnt out
Fault no. 5
Twin conductor
with screen
Will not show No heat
Fault no. 1
RCD-relay cut o
or fuse is burnt out
Fault no. 4
Burnt fuse
Fault no. 5
= No action!
= Not possible!

DEVItector™ II V2User Guide
BC421332622232en-010101 2022.07 | FEC | ©Danfoss | 17
Gallery of Heating Cable Faults
Fault no. 1 : Conductor is (L or N) disrupted and screen is present
1
2A
2B
Fault no. 2: Conductor (L or N) disrupted and no screen is present
A connection cannot be measured in the heating
conductor (innite resistance or a decreased
conductivity).
In this case the idea is to burn a connection between
the disrupted conductor and the other conductor.
This is done by burning between the two conductors,
to create a carbon compound at the point of disruption.
The carbon bridge is then used for tracing.
No connection can be measured in the heating
conductor (innite resistance or very high resistance
as compared to the heating wire).
The insulation resistance of the heating cable is
assumed OK.
In this case the idea is to burn a connection or carbon
bridge (shown as a small yellow box) between the
disrupted conductor and the screen. The carbon
bridge is then used for tracing. In case of a single
conductor [1] the burning is straight forward.
In case of a twin conductor [2], one of two situations
may occur:
2A: The carbon bridge connects to the shortest part of
the disrupted conductor. This case may be traced
directly.
2B: The carbon bridge connects to the longest part of
the disrupted conductor. This case is not traceable,
as the tracing signal will radiate from the entire
length of the cable.
Note: In cases [1] and [2A] a further situation may
occur. The screen typically is formed by a bundle of
wires which may or may not touch each other along
the length of the cable. Imagine that some of the
screen wires are disrupted and the carbon bridge
connects to the right side of one of these. Then the
tracing signal will extend from the cold cable until
the point at which the connected screen wire touches
one of the undisrupted screen wires, much like the
situation in case [2B].
If a twin cable cannot be traced like in [2B], try to burn
a carbon bridge between the two conductors.
The blue bars on the pictures above are shown the
area of tracing signal availability.

DEVItector™ II V2User Guide
BC421332622232en-01010118 | ©Danfoss | FEC | 2022.07
Fault no. 3 : Screen/conductor short circuit, i.e. a high leakage current may be measured
The resistance of the heating cable is OK. It is possible
to measure a nite resistance between conductor
and screen. The value will depend on the distance
between cold cable and fault.
In this case the idea is to use the short circuit between
conductor and screen for tracing.
No burning is required unless the short circuit turns out
to be unstable.
Fault no. 5 : Conductor (L/N) short circuit
The resistance of the heating cable is reduced,
depending on the distance between cold cable and fault.
The insulation resistance of the heating cable is OK.
In this case the connection between the two
conductors is used for tracing. No burning is required
unless the short circuit is unstable.
Fault no. 4 : Screen/conductor short circuit
The resistance of the heating cable is OK.
It is possible to measure a nite resistance between
conductor and screen. The value will depend on the
distance between cold cable and fault.
In this case the idea is to use the short circuit between
conductor and screen for tracing.
No burning is required.
As the end-terminated heating conductor is not
disrupted, the shortest path from cold cable to fault
is the one with the least resistance assuming identical
resistances of the two conductors. The longest path
(the lower conductor on the above sketch) will emit a
magnetic eld along the entire heating cable.
Thus only the conductor having the shortest path will
make the tracing possible.
If it is impossible to determine the conductor
having the shortest path, it is necessary to trace the
cable twice, rst with one and then with the other
conductor, respectively.

DEVItector™ II V2User Guide
BC421332622232en-010101 2022.07 | FEC | ©Danfoss | 19
Fault no. 1 and no. 3: Conductor is (L or N) disconnected and screen/conductor short circuit
A poor connection can be measured through the
heating conductor (innite or too high resistance). A
nite resistance between screen and conductor may
be measured.
In this case the short circuit between conductor and
screen is used for tracing. No burning is required.
By measuring the resistance between the screen
and the two conductors (L and N), you may be able
to locate the heating conductor having the shortest
distance to the fault.
Fault no. 1 and no. 4: Conductor is (L or N) disconnected and screen/conductor short circuit
No connection is measured in the heating conductor
(innite or too high resistance). The insulation resistance
also shows a fault, and it is possible to measure a nite
resistance between conductor and screen.
In this case the connection between conductor and
screen is used for tracing.
Fault no. 4 and no. 5 : All three conductors (L, N, screen) short circuit
The resistance of the heating cable is reduced depending
on the distance between cold cable and fault.
The resistance between screen and anyone conductor
is nite, signifying a short circuit. In this case, the
tracing may be carried out using any two conductors
of the heating cable.
As shown in the examples it is recommended to use the authorised cable testing equipment to facilitate the
choice of the troubleshooting process.
In some cases you may go directly to tracing, and in some cases you will need to burn the necessary connection
for use in the tracing process.
For appropriate use of the equipment, please proceed to the next section.

DEVItector™ II V2User Guide
BC421332622232en-01010120 | ©Danfoss | FEC | 2022.07
8. Burning and Tracing
When the cable fault is a disruption or a weak
connection (high resistance), the burning procedure
should be followed.
WARNING
Hazardous voltage on terminals. Keep hands
away from terminals and connected cable.
WARNING
If the heating cables are not completely covered
by non-ammable materials such as sand or
concrete, and close to ammable material, cable
burning procedure should be undertaken with
great caution as the heating cable will burst into
open ames at the fault location.
WARNING
Burning can produce smoke – secure ventilation
of the room.
Fig. 22: Photo of HVU-treated heating cable installed
in open air on sand
Overload protection
The DEVItector™ II V2 unit has several built-in overload
protection modes.
Burning mode
A software-controlled reversible thermofuse monitors
two power resistors. If their temperature exceeds 75 °C
the display will show the message“Power Resistors
Overheated” and you will have to let the HVU cool
down for several minutes before proceeding.
Note: Do not switch power OFF when HVU is cooling
down because of possible work of fans.
The temperature sensor itself is monitored. If it should
disconnect, the display will show the message“NTC
disconnected”. If it is shorted, the display will show
“NTC shorted”. In both cases, authorized repair will be
needed.
The DC voltage is limited by software to yield a
maximum of 3A current. The limiting is automatic and
requires no user intervention.
Resetable thermo fuses
If DEVItector™ is in Burning mode and does not
produce sparks the resettable thermo fuse could be
OFF. The thermo fuse will automatically restore On
condition after approx. 10–20 min.
Note: Do not switch power OFF when HVU is cooling
down.