1 ) Closed-circuit
mode :
In this mode, live lines are
tested with a potential of a maximum of 300 V to ground.
The signal current of the signal generator, for example, is fed into
the phase of the line to be tested and flows back to the signal
generator through neutral conductor across the transformer.
This "two-pole" application corresponds to a closed
circuit, whereby the energy for the generation of the signals is
directly derived from the system. In the case of a shorted line, the
current flow in the circuit to be measured is interrupted, a 9-V
battery can, for example, be connected into the measuring circuit as
a substitute power supply.
The receiver evaluates the magnetic component of the signal.
2) Open-circuit mode
:
In this operating mode, only
electrically dead lines may be tested.
One output of the transmitter
is connected to the line to be tested, the second output to
ground.
This "single-pole" application corresponds to the
principle of a radio transmitter.
The connected line hereby becomes the antenna of the transmitter,
the ground serves as reference potential.
The energy for the generation of the signals is provided by the
internal battery.
The receiver evaluates the electrical component of the signal.
2.1 Receiver
R300
The receiver R300 has two built-in
detectors which receive the different signals from the signal
generator for live and electrically dead lines. These signals are
indicated both optically and acoustically:
Optically by a diode assembly with which up to 10 diodes light as a
function of the signal strength.
A red filter permits reading also in the case of direct incidence of
sunlight.
Acoustically by a sound generator.
2.2 Signal
generator S330 for live lines
The signal generator S330 sends
high-frequency electromagnetic signals which the receiver R300 can
locate along the line to be tested. For this purpose, the signal
generator must be connected to this line as well as to a return
line.
The signal generator is designed for lines having AC or DC voltages
from 9 to 300 V.
The signal power of this unit can be switched to a lower power so
that circuits protected by residual-current circuit breakers can
also be connected.
2.3 Transmitter
T320 for electrically dead circuits
The transmitter T320 sends high-frequency
electromagnetic signals the electric or magnetic component of which
can be detected along the line to be tested by the receiver R300.
For this purpose, one socket of the transmitter must be connected to
this line. The second socket must be connected to ground.
The unit requires a 9-V battery for the power supply.
An additional,
external power source, e.g. a 24-V NiCd storage battery, leads to a increase in
performance.
Storage batteries in the battery compartment are not charged via the
external power source.
3 Measurements on
live lines with the signal generator S330
3.1 Closed-circuit
mode
In this operating mode, live
lines are tested with a potential having a maximum of 300 V to
ground.
The load current normally flows in the phase in opposite direction
to the neutral conductor,
see connection A. This way, the also opposite magnetic fields are
weakened, causing a loss
in signal strength in the receiver. The depth of detection is
reduced.
The same applies when the current flows back across the protective
conductor, see connection B.
3.2 General procedure
for live lines
Signal generator.
If the measuring circuit has no residual-current circuit breaker,
select the highest signal
amplification.
