What is an instrument and audio transformer

What is a transformer

A transformer is an electrical device, which can transfer electrical power inductively. It operates at a particular current and voltage of one circuit to another circuit which is operating at different voltage and current levels. Transformers are manufactured in a certain manner that their characteristic should match for special requirements such as constant current, constant voltage, etc. There are many types of transformers like isolation, distribution, power, etc each of them has its own functions and applications. A distribution transformer can be used to transfer electrical loads to the customers at the required voltage rate.

Isolation transformer

Transformer testing

Transformer types

What is an instrument transformer and what is its use

Instrument transformers are used to protect or isolate the metering equipment, relays, instruments and other control devices from the circuit which is operating at high voltages and currents and in which electrical quantities are to be measured. These are specially designed for the use of electrical instruments such as ammeters, voltmeters, wattmeters, protective relays, energy meters… to increase their range of measurement. These transformers would be able to serve equipment that does the conversion of voltage and current, from a high voltage circuitry to the level which is suitable for measurement. The instrument transformer is classified into a current and voltage transformer. Instrument transformers are used for the accurate measurement of the current or voltage Instrument transformers transforms the high current or high voltage connected to their primary windings to the standard low values in the secondary within the required accuracy limits which feed the metering and protection apparatus. It can provide insulation against high voltage and can protect personnel and apparatus from high voltages. Instrument transformers can be used for protection and control of the power system. Instrument transformers are important apparatus used in transmission and distribution networks.

What are the types of instrument transformer

There are two types of instrument transformer they are current and voltage transformer

CURRENT TRANSFORMER – Working, types, & connection

VOLTAGE TRANSFORMER – Working, construction, connection, & types

What is a burden in instrument transformers

To energize protective relays and other equipment, primary quantities are reduced by the turn ratio in order to provide a secondary current or voltage. The totality of the impedances of the loads connected to the current and voltage transformers is referred to as a burden.

What are the basic function of an instrument transformer

Its major function is to provide insulation between primary and secondary circuits for equipment and personnel safety. To change the magnitude of the quality being measured to a suitable level for use with standard instruments.

What is a combined instrument transformer

This type of transformers has both current and voltage transformers in a single standing unit. This type of transformer can convert voltage and current to the standardized low and measurable values which are useful for metering protection and other high voltage control systems. By using this transformer we could minimize the use of space and the supporting structures and the mounting pads are used less. Combined instrument transformers are mostly used in protective relaying and revenue metering applications.

What are the advantages and disadvantages of instrument transformer

By connecting long wires to the instrument transformer the measuring instrument can be placed far away from the high voltage side and this will ensure the safety of the instrument and the operator. These transformers can be used to increase the range of measuring instruments like ammeters and voltmeters. The only disadvantage is that this transformer cannot be used in DC circuits.

What is an audio transformer

An audio transformer is a transformer that is used to carry the audio signals in an audio circuit. The working frequencies of this transformer range from 20Hz to 20KHz. This transformer can convert a circuit from balanced to unbalanced and vice versa, it can decrease or increase the impedance of a circuit, it can block the DC component of current and allow AC signal, and these transformers can also provide electric galvanic isolation from one audio device to the other. These types of galvanic isolation include a microphone input, line input, moving-coil phono input, line output inter-stage, and power output, etc. The audio transformer is mostly designed for audio circuits, these transformers can block radio frequency interface. Initially, audio transformers were used to connect the different telephone systems to one another. These transformers are still used to interconnect professional audio systems or system components. Audio transformers are susceptible to the external magnetic fields because they are magnetic device, the magnetic fields could be generated from the AC current-carrying conductors. The term ‘HUM’ is used to describe the unwanted signals which originate from ‘mains’ power supply.

What is the use of audio transformer

Audio transformers are used because they have two useful properties, first is they can benefit circuit performance by transforming circuit impedances. Second is there is no direct electrical connection between its primary and secondary windings, so this transformer can provide electric or galvanic isolation between two circuits.

How audio transformer is constructed

The construction of an audio transformer varies from the regular power transformer, in this, the leakage inductance must be kept as low as possible. The interleaving is covered for the leakage inductance. The windings must be above one another. The margins called out to be maintained and the winding lengths must be fully utilized. If the turns are not sufficient to fill out the winding length then the wire must be spiraled to fill it out. The margins of all windings must be same and windings when layer wound, must be even and no cross overs allowed. So by considering all these factor audio transformers can be constructed, sloppy construction will result in a failed transformer.