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detector contact electrode is in contact with the live conductor. If
the voltage on the conductor is less than the threshold voltage of
detector, then High Bright Red Leds and the audible alarm will not
16. Interference voltages
the detector may occur.
Erroneous indication will only occur if the body of the detector is
Correct indication can be achieved by applying the detector
to horizontal conductors away from bends or connections.
Unambiguous indication of the detector depends upon the
capacitance of the detector to earth being unaffected by other
In-Phase Interference
This occurs when the conductor under test is adjacent to another
conductor whose voltage is in-phase.
detector and earth, thereby reducing the effective capacitance of
the detector to earth.
This results in an increased threshold voltage which could mean
that the detector will not indicate that a conductor is live.
This increases the threshold voltage of the detector which may,
therefore, not indicate. This is of course a dangerous situation.
Phase-Opposition Interference
If a conductor under test has adjacent conductors which are
in phase opposition, then erroneous indication can occur. For
instance, if the conductor under test is earthed and the detector
came close to a live conductor then it is possible that the detector
will indicate that the conductor under test is live. This, however,can
be seen as a fail safe condition, although it is incorrect.
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17.
Electrical
Threshold Voltage:
For
a single voltage detector (for example 11kV) the threshold
voltage should be in the range 0.15 X detector voltage to 0.4 X
detector voltage i.e. for 11kV, V
THRESHOLD
is in the range 1.65 to
4.4kV.
For a detector with a
two to one voltage range (for example 66
to 132kV) the threshold voltage should be in the range 0.15 X
detector maximum voltage to 0.4 X detector minimum voltage
i.e. for 66/132kV, V
THRESHOLD
is in the range 19.8 to 26.4kV.
For a detector with a
three to one voltage range (for example
11 to 33kV) the threshold voltage should be in the range 0.1
X detector max. voltage to 0.45 X detector min. voltage i.e for
11/33kV,V
THRESHOLD
is in the range 3.3 to 4.95kV.
Where none of the above rules can be applied the
threshold may
be set to a value agreed with the customer.
Accuracy of threshold voltage: ±5% of set level and under our
factory test and setup conditions.
Operating Time:
About 3 minutes nominal with VOLTAGE NOT
PRESENT on the contact electrode.
Continuous with VOLTAGE PRESENT on the contact electrode.
Response Time:
Less than 1 second.
Spark Protection:
The detector will not be damaged as a result
of spark discharge while making contact with the conductor under
test.
Bridging Protection:
The detector and its accessories will not
or between live parts of the installation and earth.
Current Consumption:
30mA maximum.
Battery Low:
7.2V nominal (Arming via the testing/arming
button is inhibited at this voltage but self-arming from signals is
maintained down to 6.5V.)
Battery:
9 V manganese alkaline PP3-C IEC 6F22.
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