ZC-7型兆欧表英文说明书

TYPE ZC-7 INSULATION TESTER

TPYPE ZC-7 INSULATION TESTER

Application

Type ZC-7 portable insulation tester is used for measuring the insulation resistance of transformers, cables, electrical, machines and apparatus.

Construction

The tester consists of a hand-driven A.C. generator, Silicon diode rectifier and an internal magnet type cross current ratio meter. The instrument is enclosed and tightly sealed in a diecast Aluminium case.

Outstanding feature

1.Long scale-over 80mm:clear scale and wide range;

2.Silent generator-the rotary magnet type generator turns

extremely smooth and silent. The generated voltage is not over 120% of the rated voltage at the crank speed more than 120 r.p.m.;

3.No adjustment required-calibration is not necessary before

measurement. The tester is simple and easy to operate;

4.Perfect screen –measuring of the insulation resistance to

earth,the instrument is so designed the earth current can not affect the measurement in any way;

5.Perfect external magnet shield-the indicator employs a core

magnet system in which eht yoke acts as a self-shield makes the external magnet field influence quite negligible;

6.Little and light-the instrument is housed in a gray diecast

Aluminium case, so it is little in volume, and light in weight;

7.Tightly sealed-the tester is so tightly sealed to prevent the

ingress of moisture.

Operating principle

The indication movement consists of two master coils, current coil L1, and voltage coil L3, are fixed at an angle to one another. Coil L1is connected through terminals L and E in series with the resistance to be measured. Coil L3 is connected across the D.C. voltage supple, which is generated from the D.C. converting systems. When current flows through them, coil L1Produces the deflecting moment which is inversely proportional to the resistance under test, coil L3produces the control moment which is directly proportional to the supply voltage.

The turning moment of the coil L3tends to turn the pointer in an anti-clockwise direction, while the coil L1tends to cause clockwise direction.

The balance position of the pointer is such that these two turning moment are equal.

Thus the instrument gives directly the value of the resistance to be measured.

W: Generator winding R1: Current circuit resistance C: Double voltage R2: V oltage circuit resistance S: Silicon diode L: Line terminal

L1: Compensating coil of indicator E: Earth terminal

L2: V oltage coil of indicator

Type ZC-7 Insulation Tester Circuit Diagram