Construction of Electrodynamometer – The electrodynamometer wattmeter has a fixed coil divided into two parts and is connected in series with the load and caries the load current (I 1 ). The moving coil is connected across the load through a series multiplier resistance (R) and carries a current (I2) proportional to the load voltage.

What is the construction of electrodynamometer wattmeter?

Fixed Coil – Fixed coil or CC is carries the circuit current. It is divided into two halves. Fixed coil is chosen as a current coil as it can be made more massive. Therefore they can easily carry heavier current. Fixed coil is wound with heavier wire. The wire is either stranded or laminated to avoid eddy current loss,

What is the current coil in an electrodynamometer wattmeter?

Electrodynamometer Wattmeter are often used for the measurement of power consumption. The construction of such instrument similar to the construction of electrodynamometer type ammeter and voltmeter, An electrodynamometer wattmeter have two types of coils.

• One coil is fixed and another coil is moving.
• The fixed coil is connected in series to the circuit whose power consumption is to be calculated.
• Therefore this fixed coil is often called Current Coil or simply CC.
• Moving coil is connected across the supply voltage.
• Due to this current proportional to supply voltage flows through the moving coil.

To limit the current through this coil, a resistor is connected in series with the moving coil. Moving coil is called Pressure Coil or simply PC.

What is a directdynamometer type wattmeter?

Electrodynamometer Type Wattmeter – Working, Construction & Diagram In this topic, you study Dynamometer Type Wattmeter – Working, Construction & Diagram. Dynamometer Type Wattmeter is similar to the dynamometer type ammeters and voltmeters. The dynamometer instruments are used more as wattmeters, as they are expensive (Fig.1.).

1. The fixed coil which is divided into two equal coils is used as ‘”current coil (CC) ” and the moving coil is used as a “pressure coil (PC).
2. The current coil carries full load current, whereas the pressure coil carries a current proportional to the voltage across the circuit.
3. The moving coil carries a pointer.

The interaction of the magnetic fields of the current coil and sure coil produces a torque and makes the pressure coil to move. The pointer attached with it also moves and gives deflection on a calibrated scale. The controlling torque is produced by springs and damping torque by air damping. Fig.1. Dynamometer Type Wattmeter. The Fig.2 shows connections of wattmeter to measure power. The high impedance CC is connected in series and low impedance PC is connected in parallel. This reduces error and the instrument is called compensated wattmeter. Fig.2. Wattmeter Connections. The Fig.3 shows practical connections of the wattmeters in the laboratory. The M and L are the terminals of current coil (Fixed coil). The M is to be connected with the “SUPPLY” and L with the “load”. Fig.3: Connection of Dynamometer Type Wattmeter.

Why dynamometer instruments are used more as wattmeters?

Electrodynamometer Type Wattmeter – Working, Construction & Diagram In this topic, you study Dynamometer Type Wattmeter – Working, Construction & Diagram. Dynamometer Type Wattmeter is similar to the dynamometer type ammeters and voltmeters. The dynamometer instruments are used more as wattmeters, as they are expensive (Fig.1.).

1. The fixed coil which is divided into two equal coils is used as ‘”current coil (CC) ” and the moving coil is used as a “pressure coil (PC).
2. The current coil carries full load current, whereas the pressure coil carries a current proportional to the voltage across the circuit.
3. The moving coil carries a pointer.

The interaction of the magnetic fields of the current coil and sure coil produces a torque and makes the pressure coil to move. The pointer attached with it also moves and gives deflection on a calibrated scale. The controlling torque is produced by springs and damping torque by air damping. Fig.1. Dynamometer Type Wattmeter. The Fig.2 shows connections of wattmeter to measure power. The high impedance CC is connected in series and low impedance PC is connected in parallel. This reduces error and the instrument is called compensated wattmeter. Fig.2. Wattmeter Connections. The Fig.3 shows practical connections of the wattmeters in the laboratory. The M and L are the terminals of current coil (Fixed coil). The M is to be connected with the “SUPPLY” and L with the “load”. Fig.3: Connection of Dynamometer Type Wattmeter.

Nehru Baral