DIGITAL MICRO-OHM METER
53C
ABVOLT TECHNOLOGIES
INCORPORATED
MUMBAI
ABVOLT 53C DIGITAL MICROOHM METER
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INTRODUCTION
Model 53C is compact 31/2 digit. digital Micro Ohm Meter suitable for
measurement of resistance of cables, wires, small transformers, motors
winding, coils and contact resistance of switches, connectors, relays and
track resistance of PCB's etc; for the manufacturers and incoming
inspection of the same for the users, testing and calibration centers and
R & D Laboratories. The usage of the latest MOSLSI Technology has
helped in increasing the reliability.
The actual value of the resistor is displayed on bright 7 segment type of
LED display. Four terminals measurement system for low values
provides measurement free from errors due to contact resistance and
test cables resistance.
ABVOLT 53C DIGITAL MICROOHM METER
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SPECIFICATIONS
RANGE :1 micro ohm to 19.99 kohms in 8 ranges of 1999 micro ohm,
19.99 milli ohm, 199.9 milli ohm, 1999 milli ohm, 19.99 ohms , 199.9
ohms, 1999 ohms and 19.99 kohms
ACCURACY: + 0.5% + 2 digits in 1999 micro ohm, 19.99 milli ohm,
199.9 milli ohm, & 1999 milli ohm ranges, ± 0.2% ±1 digit in 19.99 ohms,
199.9 ohms, and 19.99 kohm ranges
DISPLAY: 31/2 digit, RED LED seven segment
TEST CURRENT :
Range
1999 micro ohm
19.99 mohm
199.9 mohm
DC Current
1 amp
1999 ohms
19.99 ohms
199.9 ohms
1999 ohms
19.99 kohms
0.1 amp
0.01 amp
0.001 amp
0.0001 amp
0.00001 amp
POWER : 230 V, 50Hz
5 VA
SIZE : Size : 85 mm (H) x 195 mm (W) x 230 mm (D)
WEIGHT : Weight : 4 kg.
ABVOLT 53C DIGITAL MICROOHM METER
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CONTROLS, CONNECTIONS & INDICATIONS
POWER ON : When turned on, the power is applied to the unit and the
display is turned on
RANGES : Select the range of the resistor to be tested . The usage of
lowest possible range is recommended to get highest accuracy and
better resolution, The settings for various ranges of resistance values are
given below
RANGE
VALUE RANGE
1 micro ohm to1.999 milli ohm
10 micro ohm to 19.99 milli ohm
0.1milli ohm to 199.9 milli ohm
1 mili ohm to 1.999 ohm
0.01 ohm to 19.99 ohm
0.1 ohms to 199.9 ohm
1 ohms to 1999 to
10 ohms to 19.99 kohms
SETTING OF THE
1999 micro ohm
19.99 milli ohm
199.9 milli ohm
1999 milli ohm
19.99 ohms
199.9 ohm
1999 ohm
19.99 kohm
TEST RESISTOR: Connect the terminals to the resistor under
measurement. In order to avoid signal pick-up from the environment the
usage of shielded for high value resistor is recommended. In order to
reduce the effects of contact resistance of test terminals and resistance
of test cables, four terminal measurement system have been
incorporated. Under this arrangement the "ILo" and "IHi" terminal
provides the precision current to be passed through the resistor while "
VLo" and "VHi" terminals measure the voltage drop directly across
current carrying test terminals and cables are not measured by the DVM
and display of the true value of the resistance is provided.
DISPLAY : It display the value of the resistor or test element. It also
shows the over range indication as 1 if the value exceeds the set range
and also if there is an open circuit.
ABVOLT 53C DIGITAL MICROOHM METER
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THEORY OF OPERATION
The circuit diagram of Model 53-C is enclosed. The basic circuit consists
of precision current source whose value is determined by the setting of
range control. The current from the current source is passed through test
resistor and the voltage drop across the test resistor is measured by a
precision digital milli voltmeter. Since the voltage drop across the test
resistor is directly proportional to its value, the display is also directly
proportional to its value. The value of currents and sensitivity of DVM
have been so selected that the display value is the same as the actual
value of the resistance value. The decimal point indication for the display
of the value is also automatically selected by the range control.
The main voltage is applied to the primary winding of the transformer
through fuse and power ON switch. The voltages generated at the two
secondary winding of the transformer are rectified by rectifier diodes
filtered by condensers and regulated by IC Circuit and associated
components THE DC stabilized and regulated supplies of +5, -5, +12, & 12 Volts made available from the power supply circuit. These regulated
Supply outputs are used in constant current generator and DVM circuits .
IC2, IC3, and associated components form the constant current
generator. The value of constant current is determined by the setting of
RANGE CONTROL SWITCH which also determines the positions of
decimal indication for its various positions. The constant currents
generator is fed to the test resistor terminals. The voltage developed
across the test resistor is measured by a precision 31/2 digit, Digital milli
Voltmeter consisting of ICI and associated components. The output is
displayed on 7 segment LED display.
Each setting of the range switch can be individually calibrated by R -1
through R-6. Four terminals connections for current source and DVM
help to avoid errors accused in low resistance measurements due to
connector contact resistance and test cable are not measured and the
voltage drop across test resistor is directly applied to DVM. The
resistance of connectors and test leads for voltage measurements are
low as compared to the input impedance of 1000 Trillion ohms of the
DVM and are negligible - Hence this arrangement ensures the true
measurement of low resistance value without lead resistance.
ABVOLT 53C DIGITAL MICROOHM METER
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FIRST TIME OPERATION
Before Turning the instrument 'ON ' ensure that the function and usage
of each control has been properly understood. Incomplete knowledge
may give misleading results. It is recommended that the user
understands this manual before proceeding further
Before turning the instrument "ON", ensure that the earth pin of the
power plug is securely connected to earth (Power Line) ground. Always
use 3 – wire grounded outlet which conforms to the latest electrical
specifications.
Connect the power plug to 3 - wire grounded outlet . Turn on the power
and connect the test lead to the test resistor terminal of the instrument.
Black leads of the test LEADS should be connected to black terminals
and similarly red leads to red terminals. Now connect the two red leads
to one end of the test resistor and the two black leads to the other end of
the test resistor.
HOW TO GET ZERO :
Short VHi and VLo & adjust Zero using zero adjustment pot below range
selector switch.
WARM UP TIME
: 5 to 10 minutes for stability of circuitry
ABVOLT 53C DIGITAL MICROOHM METER
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