The 275 HP is a high voltage proximity detector.
It has eight voltage detection settings from 240Vac to 275kVac.
The 275 HP consists of an internal pickup sensor plate, a sensitivity selector, and both visual and audio annunciators.
Physical contact with electrical conductors is not necessary when testing for live lines since the 275 HP has a proximity sensor.
It senses the radiated field which surrounds live conductors.
Radiated field strength increases with voltage and decreases quickly with distance or earth shielding.
( Please See “Limitations of use” paragraph in the instruction manual).
Detecting distance of a 250Vac single live wire is approximately 10cm.
With a bunched neutral and earth cable, as in a flexible cable, the distance is reduced to 5cm.
Some typical uses of the 275 HP are:
1) Identifying and checking live cables,
2) Finding faults in flexible cables,
3) Tracing live wires,
4) Checking high frequency radiation, and
5) Detecting residual or induced voltages.
For example, faults in damaged flexible cables are found by applying low voltage to each conductor, earthing the remainder, and moving the tester along the cable until a change in condition is obtained.
(Flexible cables which are used in mining and building industries, are readily repairable when the break in the cable is located.)
When testing for high voltage, the rotary switch (attenuator) is used to identify and differentiate various H.V. live cables.
The detector must be used in conjunction with a long insulated rod when measuring high voltage (kV).
The 275 HP is a non-contact proximity tester only, and should never come into contact with live high voltage wires.
Checking or proofing the tester is easy.
Switching the sensitivity to 240V and placing the dome against a low voltage live conductor, or rubbing the dome with a cloth or an item of clothing, generates a static DC which triggers the detection circuit.
The light and beeper should go “on” as if a live wire is being detected.