PMMC
DC METERS
MOVING IRON
DYNAMOMETER
Shunt-Type Ohmmeter
When Rx = 0, no current in meter.
When Rx = ∞, entire current flows through the meter.
Proper selection of R1 gives full-scale deflection on open
circuit.
DYNAMOMETER TYPE INSTRUMENTS
For both ac & dc measurements
• These instruments are similar to the permanent
magnet type instruments, except that the permanent
magnet is replaced by a fixed coil.
• The coil is divided into two halves, connected in
series with the moving coil.
• The two halves of the coil are placed close together
and parallel to each other to provide uniform field
within the range of the movement of moving coil.
DYNAMOMETER TYPE INSTRUMENTS
Electrodynamometer Type
04‐03‐09
Nkp/eee skcet
DYNAMOMETER TYPE‐Ammeter & Voltmeter
MOVING‐IRON INSTRUMENTS
For both ac & dc measurements
• Attraction (or Single‐iron) Type Moving‐Iron Instrument
Repulsion (or Double‐Iron) Type Moving‐Iron Instrument