Instruments & Measurements

A galvanometer with a 20 ohms coil resistance has a full scale deflection of 10 mA. A 0.02 ohm is placed across the meter to increase its rated capacity. What is the new full scale current for the meter?

The potential transformers of a line have a ratio of 132,000/66. These are connected wye-delta. The voltmeter reads 64 V. What is the voltage of the line?

A current of 20A flows through two ammeters A and B joined in series. Across A, the potential difference is 0.2V and across B, it is 0.3V. Find how the same current will be divided between the two when they are joined in parallel.

A 200:5 current transformer is used with a 10 amps ammeter. If the meter reads 4.5 amps, determine the line current.

A dc ammeter has an internal resistance of 0.1 ohm. A shunt of \(1.01 \times 10^{-3}\) ohm is connected to the ammeter. What is the multiplier of the set up?

Calculate the force that will be exerted on the scale in pony-brake test when a 20-HP, 1,400 rpm motor is operating at full-load. The length of the brake arm is 3-ft, and the tare weight of the brake is 3.75lb.

The input power to a 3-phase induction motor running without load is measured by the two wattmeter method. One wattmeter indicates −220 watts and the other indicates 940 watts. What is the no-load power factor of the motor?

A sinusoidal current having peak value 7.07 A is superimposed on dc of 5 A. If a hot-wire ammeter is used to measure the combined current in the circuit, it will indicate ___ amperes.

A meter has a full-scale current of 50 μA. What is its sensitivity?

Power in balance 3-phase system is measured by the two-wattmeter method and it is found that the ratio of the two-wattmeter readings is 2 is to 1. What is the power factor of the system?

What is the total power consumed by the load when the readings of two wattmeters are 5 kW and -0.5kW?

Given a 100 kVA 2,400/240 v single phase transformer. Find the current transformer (CT) ratio at the low voltage side.

A moving coil instrument requires 50 mA and 100 mV for full-scale deflection. What is the value of the shunt required to convert it to read up to 5 A?

A dc ammeter has an internal resistance of 0.1 Ω. A shunt of \(1.01 \times 10^{-3}\) Ω is connected to the ammeter. What is the multiplier of the set up?

The ratio of the wattmeter readings in three-phase inductive system is 2:1 when power is measured by the two-wattmeter method. What is the power factor of the load?

At a 115 kV substation, the PT ratio is 1,000 and the CT ratio is 1200/5. The potential going into the wattmeter is 115 volts. What is the MW indicated when the wattmeter reads 800 watts?

A dc ammeter has an internal resistance of 0.1 Ω. A shunt of \(1.01 \times 10^{-3}\) Ω is connected to the ammeter. What is the multiplier of the set up?