DEVItector™ II V2
User 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 (infinite 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 (infinite 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.
