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Resistance Meter ZC25 Earth Resistance Tester
Resistance Meter ZC25
Instruction Resistance Tester
APPLICATION
This Tester is used for measuring high resistance and testing
electrical lines, windings of motors and generators, cables or
other electrical installations during their installation, running,
maintenance, repairs, etc. It can also be used as a common
insulation tester.
CONSTRUCTION
This Tester consists of a hand-driven high voltage generator and an
internal magnet cross coil current ratio meter. The current ratio
meter adopts the new internal magnet type to provide steady and
accurate readings .It is practically not sensitive to the influence
of external magnetic fields.The hand-driven generator is equipped
with a centrifugal governor which enables the rotor to rotate with
constant speed for maintaining steady output voltage.This Tester is
provided with a "Guard" terminal to prevent errors due to surface
leakage, thus ensures accurate readings.
4. The Tester is enclosed in a light metal case, tightly sealed to
prevent the ingress of moisture.
TECHNICAL DATA
TYPE VOLTAGE RANGE MIN.SCALE
0101T 100V 0-100MΩ 0.05 MΩ
2525T 250V 0-250 MΩ 0.05MΩ
5050T 500V 0-500 MΩ 0.1MΩ
1010T 1000V 0-1000 MΩ 0.2 MΩ
Length of scale: Approx.65mm
Accuracy: Not over±1% of full scale length
Standard testing: Temperature & 20ºC±2ºC, 65±15%
Relative Humidity:
Cranking Speed: 120rpm
Inclination Variation: Not over±1% of full scale at an inclination
of10°
Temperature Variation: Not over±0.8% of full scale for
every±10°change in ambient temperature.
External Magnetic Field Influence: Not over±2.5% of full scale
length at a magnetic field influence of 5O rested.
Inclination Resistance: Not less than 20 me ohms at20°±2ºC and
relative humidity of 65±15%.
Dimensions; 210x120x150mm
Weight: Approx. 2.5kg
MAINTENANCE AND UPKEEP
1. In time of use, the Tester should be placed far away from
magnetic fields and in level, stable position.
When measuring, first rotate the handle clock wise until the speed
increases gradually up to approximately 120rpm at which the
governor begins to slip and steady readings then be taken.When
measuring insulation resistance, connect the two terminals of the
object to "Earth" and "Line" respectively, then rotate the handle
and take the readings.When making "Earth" test, connect the object
terminal to "Line" and a good earth wire to "Earth" terminal.When
measuring insulation resistance between cable core and sheath,
besides connecting the two terminals of the object to "Earth" and
"Line" connect also the intermediate insulation layer between the
core and sheath to "Guard" to eliminate possible surface leakage
which may cause errors in readings.Stand wire cords being well
separated, should not be used as testing leads between the
terminals of the object in order to avoid incorrect readings due to
inadequate insulation.The use of the Tester under thunder-bolts or
in the vicinity of high tension installations should be prohibited.
It may only be used when the object is not charged or electric
sources.Before and after measuring, the object must be discharged
completely to ensure safety of personnel and installations.The
rotating speed of the handle should be increased gradually. If the
pointer is found to remain at 0, the operation should be
discontinued at once to prevent the tester from damage.Violent and
continuous vibrations should be avoided as far as possible, so that
the pivot of the tester may not be damaged or the sapphire bearing
broken thereby affecting the accuracy of the tester.When not in
use,the tester should be placed in a cabinet at ordinary room
temperature. It should never be put on dirty or wet grounds, or at
the place where the air is contaminated with alkaline and/or acid
vapors.
Rc - Current circuit resistor
Rp - Voltage circuit resistor
Nc - Current circuit coil of indicator
Np - Voltage circuit coil of indicator
F - Generator
Circuit Diagram
FAQ