What do you mean by instrument transformers, Electrical Engineering

Assignment Help:

Q. What do you mean by Instrument transformers?

These are generally of two types, potential transformers (PTs) and current transformers (CTs). They are designed in such a way that the former may be regarded as having an ideal potential ratio, whereas the latter has an ideal current ratio. The accuracy ofmeasurement is quite important for ITs that are commonly used in ac circuits to supply instruments, protective relays, and control devices.

PTs are employed to step down the voltage to a suitable level, whereas CTs (connected in series with the line) are used to step down the current for metering purposes. Often the primary of a CT is not an integral part of the transformer itself, but is a part of the line whose current is being measured. In addition to providing a desirable low current in the metering circuit, the CT isolates the meter from the line, which may be at a high potential. Note that the secondary terminals of a CT should never be open-circuited under load. The student is encouraged to reason and justify this precaution. One of the most useful instruments for measuring currents in the ampere range is the clip-on ammeter combining the CT with one-turn primary and the measurement functions.


Related Discussions:- What do you mean by instrument transformers

Ujt as relaxation oscillator, UJT as relaxation oscillator: The UJT re...

UJT as relaxation oscillator: The UJT relaxation oscillator is shown in fig. it consist of a UJT and a capacitor C which is charged through a variable resistance R when VBB is

Osillators.., what ie the use of mutual inductance in a hartley oscillator

what ie the use of mutual inductance in a hartley oscillator

Operation of a biased clipper and combination clipper, Q What is a clipper?...

Q What is a clipper? Describe the operation of a biased clipper and combination clipper. The circuit with which the waveform is shaped by removing (or clipping) a portion of th

Calculate rotor copper losses, A 20 h.p. , 3 phase, 400 volt, 60 hertz, 4 p...

A 20 h.p. , 3 phase, 400 volt, 60 hertz, 4 pole induction motor delivers full load at 5% slip. The mechanical rotational losses are 400W. Calculate (a) The electromagnetic torqu

State the principle of operation of a capacitor, a. Describe why a three-ph...

a. Describe why a three-phase induction motor rotates always with a speed less than the synchronous speed. b. State the principle of operation of a capacitor start single-phase

The filter capacitor , It is needed to use a half-wave rectifier for a dc p...

It is needed to use a half-wave rectifier for a dc power supply that gives an average dc output voltage of 15 V and a maximum ±1V ripple is permitted. The rectifier feeds a load of

Clipper and clamper circuit, Clipper Circuits: Clipper circuit have ab...

Clipper Circuits: Clipper circuit have ability to Clipper of portions of the input signals without distorting the remaining part of the alternating wave form. Clamper net

Perform analysis and calculate the values of vgs, A small signal amplifier ...

A small signal amplifier circuit is given in figure Q 4. The values of RD and RS must be set such that the gain of the system is 8. It is also known that Vgs = ¼ Vp. a). Per

Develop and execute a program to analyze the circuit, Develop and execute a...

Develop and execute a program to analyze the circuit shown in Figure (a), and use PROBE for plotting v C (t).

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd