I. Introduction

HZ-E-I high-voltage bridge locator is based on the MURRAY bridge principle. It is used for positioning a variety of wire and cable breakdown point or no breakdown but low insulation resistance value defect point, and high-voltage cable protection sheath faults. It can also be used for cable factory to test cable defects.

The device using SMPS to form high-voltage constant current source, no-load voltage is -15000V, short-circuit current is 30mA. Using a high sensitivity amplifier and galvanometer to indicate the balance, with the proportional potentiometer to form a balanced bridge and placed at high potential. Test line is the specially designed dual-core high-pressure rubber cable, use four-terminal resistance measurement to avoid the error arising from lead resistance, the test line is reliable grounding through braid shield, the panel operation button at the earth potential, operate the bridge through insulation bar. High voltage constant current sources and bridges are integrated in a portable industrial chassis. Therefore, the device voltage is high, light in weight, easy to operate and safe to use.

II.Function and application

HZ-E-I high-voltage bridge locator has three functions:

1 DC voltage test: the device can output 0 ~ 15kV DC voltage, can be used for cable DC voltage withstand test.

2 Burn through the point of failure: burn through and reduce the high resistance and flashover fault point resistance.

3 Fault pre-locating: Using bridge principle pre-positioning, four-terminal resistance measurement method to avoid the error arising from lead resistance.

HZ-E-I high-voltage bridge locator is particularly suitable for:

1 Installed cable high resistance breakdown point, in particular for the linear HV breakdown point which is difficult to burn to low resistance, such as cable middle connector linear high resistance breakdown.

2 Flashover breakdown point, after breakdown the constant current source can maintain the arc, a stable current through the bridge, the bridge has enough sensitivity.

3 Not yet breakdown but low resistance fault, for example, megger shows cable resistance is low, but under operating voltage the insulation defects can not be breakdown.

III.Technical parameters

1 Test voltage: 0 ~ 15kV, negative high pressure, continuously adjustable

2 The maximum current: 30mA

3 The test ratio accuracy: ± (0.2% • L ± 1) meters

4 Output voltage of outer sheath burn through: 0 ~ 15kV, continuously adjustable

5 Output current of outer sheath burn through: 30mA

6 Power source: AC220V ± 10%

7 Anti-interference ability: > 100VAC

8 Weight: ≤ 12kg

9 Dimensions: L478mm × W360mm × H316mm