2. 2/18/2015 Prabhu Mike
TONG TESTER
Tong tester is used to measure voltage and
current from the live supply wire.
Construction:
It consists of two clamps arranged in the form
of ring. One is stationary and the other is
movable due to the presence of spring.
It is commonly used in industries.
4. 2/18/2015 Prabhu Mike
RECORDER
• Recorder is a device which records electrical
and non electrical quantities as a function of
time. Current and voltages can be recorded
directly, while the non electrical quantities are
recorded indirectly.
• Types of recorders:
1. Analog recorders
2. Digital recorders
5. 2/18/2015 Prabhu Mike
• Analog recorders are further divided in to
three types:
• 1. Graphic recorder
a. strip – chart recorder
b. circular chart recorder
c. X – Y recorder
• 2. Oscillographic recorder
• 3. Magnetic – tape recorder
a. Direct recorder
b. F. M. recorder
c. pulse modulation recorder
6. 2/18/2015 Prabhu Mike
X – Y RECORDER
• X-Y recorder is an instrument which gives a
graphic record of the relationship between
two variables. We may say X-Y recorder is one
which records the variation of one physical
quantity against another physical quantity.
• It is used to measure voltage, current,
frequency, power factors etc….
7. 2/18/2015 Prabhu Mike
Construction:
• X-Y recorder consists of a pair of servo-
systems, driving a recording pen in two axis on
stationary paper chart. Attenuators are used
to bring the input signal to the levels
acceptable by the recorder.
• Two input signal are applied to the two
channels of X input & Y input.
9. 2/18/2015 Prabhu Mike
Applications
o The X-Y recorders are used in laboratories and
industrial process control. Some of the uses
are listed.
o Speed – Torque characteristics of motor.
o Lift – Drag wind tunnel rest.
o Regulation curves of power supplies.
o Plotting stress – strain curves.
o Hysterisis curves.
10. 2/18/2015 Prabhu Mike
SINGLE PHASE ENERGY METER
• There are four main parts of the operating
mechanism in a energy meter. They are
(1) Driving system
(2) Moving system
(3) Braking system
(4) Registering system
11. 2/18/2015 Prabhu Mike
Driving system
• The driving system of the meter consists of two
electromagnets. They are
1. Series magnet
2. shunt magnet
• The electromagnets is made up of silicon steel
lamination. The coil of series magnet is excited by
the load current. This coil is called current coil.
The coil of shunt magnet is connected across the
supply. This coil is called the pressure coil.
13. 2/18/2015 Prabhu Mike
Moving system
• This system consists of an aluminium disc
mounted on spindle. This disc is positioned in
the air gap between series & shunt magnets.
• The spindle top end is engaged in a bearing
cup and the spindle rests and runs on a
hardened steel pivot. The threaded portion on
top of the spindle will engage a pinion of the
energy recording mechanism.
14. 2/18/2015 Prabhu Mike
Construction
• Braking system:
The disc moves in the gap between the poles
& experiences an eddy current braking.
• Registering (counting) mechanism:
The function of a registering mechanism is
to record continuously a number which is
proportional to the revolution made by the
moving system and hence the energy in kWH.
16. 2/18/2015 Prabhu Mike
MEGGER
• The megger is an instrument used for the
measurement high resistance and insulation
resistance.
• Construction:
There are two pairs of permanent magnet,
one set for ohm meter side and the other for
the generator. The moving coil consists of
three coils namely.
17. 2/18/2015 Prabhu Mike
Cont….
(a) control coil
(b) deflecting coil
(c) compensating coil
• The unknown resistance is connected
between the terminals L & E (line & earth).
• When the pointer indicate ‘0’ hence the
resistance is very low resistance value.
