Why the efficiency of distribution transformer is 60 to 70 % and not 100%?

Why the efficiency of distribution transformer is 60 to 70 % and not 100%?
by

1 Answer

Answer :

Distribution transformer is designed for maximum efficiency at 60% to 70% load as it normally doesn’t operate at full load all the time. Its load depends on distribution demand. Whereas power transformer is designed for maximum efficiency at 100% load as it always runs at 100% load being near to generating station.
by

Related questions

At what power maximum efficiency of power transformer and distribution transformer is designed

Description : At what power maximum efficiency of power transformer and distribution transformer is designed

Last Answer : Maximum efficiency of the transformer is attained at certain load factor (α) when core losses of transformer is equal to the copper losses. PCore loss = α ^2 X PCopper loss From the ... the day. Hence distribution transformers are designed to have maximum efficiency at 50% of the rated full load

The maximum efficiency of a distribution transformer is?

Last Answer : The maximum efficiency of a distribution transformer is at 50% full load.

What are the necessary tests to determine the efficiency, voltage regulation, and temperature rise of winding & insulation of transformer?

Description : What are the necessary tests to determine the efficiency, voltage regulation, and temperature rise of winding & insulation of transformer?

Last Answer : 1.Direct loading test 2.Open circuit test 3. Short circuit test 4. Sumpner's or back to back test

Define all day efficiency of a transformer?

Description : Define all day efficiency of a transformer?

Last Answer : A:It is computed on the basis of energy consumed during a certain period, usually a day of 24 hrs. All day efficiency=output in kWh/input in kWh for 24 hrs.

What is the condition for maximum efficiency of transformer?

Description : What is the condition for maximum efficiency of transformer?

Last Answer : When Iron losses is equal to copper losses.

Define efficiency of the transformer?

Description : Define efficiency of the transformer?

Last Answer : Transformer efficiency ƞ= (output power/input power) x 100

What is the vector group of distribution transformer?

Description : What is the vector group of distribution transformer?

Last Answer : Dy11

Which type of connection is used in distribution transformer?

Description : Which type of connection is used in distribution transformer?

Last Answer : Distribution transformers are connected in delta-star. This arrangement requires 3 conductors in the high voltage side and 4 in the low voltage side, as well as it provides the star point conductor as a neutral point. This can serve single phase as well as three phase loads.

Why is an auto-transformer not used as a distribution transformer?

Description : Why is an auto-transformer not used as a distribution transformer?

Last Answer : The autotransformer cannot provide isolation between HV and LV side. Due to open circuit in the common portion, the voltage on the load side may shoot up to dangerously high voltage ... voltage on LV side is potentially dangerous. Hence the autotransformer cannot be used as distribution transformer

What are the salient features of distribution transformer?

Description : What are the salient features of distribution transformer?

Last Answer : 1. The distribution transformer will have low iron loss and higher value of copper loss 2. The capacity of transformers will be up to 500 KVA 3. The transformers will have plain walled ... with cooling tubes or radiators. 4. The leakage reactance and regulation will be low.

What are distribution transformer?

Description : What are distribution transformer?

Last Answer : The distribution transformer is used for the distribution of electrical energy at low voltage as less than 33KV in industrial purpose and 440v-220v in domestic purpose. It works at low efficiency at 60-70%, small size, easy in installation, having low magnetic losses & it is not always fully loaded.

62)The no-load current drawn by transformer is usually........percent of the full-load current? A. 0.2 to 0.5 % B. 2 to 5% C. 12 to 15 % D. 20 to 30 %

Description : 62)The no-load current drawn by transformer is usually........percent of the full-load current? A. 0.2 to 0.5 % B. 2 to 5% C. 12 to 15 % D. 20 to 30 %

Last Answer : B) 2 to 5%

48.During light loads, the transformer efficiency is low because A. Secondary output is low B. Transformer losses are high C. Fixed loss is high in proportion to the output D. Cu loss is small

Description : 48.During light loads, the transformer efficiency is low because A. Secondary output is low B. Transformer losses are high C. Fixed loss is high in proportion to the output D. Cu loss is small

Last Answer : C. Fixed loss is high in proportion to the output

42 The efficiency of a transformer will be maximum when A. copper losses = hysteresis losses B. Hysteresis losses = eddy current losses C. Eddy current losses = copper losses D. Copper losses = iron losses

Description : 42 The efficiency of a transformer will be maximum when A. copper losses = hysteresis losses B. Hysteresis losses = eddy current losses C. Eddy current losses = copper losses D. Copper losses = iron losses

Last Answer : D. Copper losses = iron losses

40 No load test on a transformer is carried out to find A. Copper loss B. magnetising current C. Magnetising current and loss D. Efficiency of the transformer

Description : 40 No load test on a transformer is carried out to find A. Copper loss B. magnetising current C. Magnetising current and loss D. Efficiency of the transformer

Last Answer : C. Magnetising current and loss

22 No load test on a transformer is carried out to find A. copper loss B. magnetising current C. Magnetising current and no load loss d.efficiency of the transformer

Description : 22 No load test on a transformer is carried out to find A. copper loss B. magnetising current C. Magnetising current and no load loss D. Efficiency of the transformer

Last Answer : C. Magnetising current and no load loss

State why a transformer always have an efficiency of more than 90%.

Description : State why a transformer always have an efficiency of more than 90%.

Last Answer : As transformer is static device with no moving parts, the losses due to friction & windage are completely absent. Hence transformer has efficiency of more than 90%.

Transformer efficiency

Description : Transformer efficiency

Last Answer : Transformer efficiency

A transformer operates 24 hours day at full -load. It's full -load efficiency is :

Description : A transformer operates 24 hours day at full -load. It's full -load efficiency is :  (A) equal all day efficiency (B) more than all -day efficiency (C) less than all -day efficiency (D) equal to maximum efficiency

Last Answer : A transformer operates 24 hours day at full -load. It's full -load efficiency is : equal all day efficiency 

Efficiency of a power transformer is of the order of?

Last Answer : The efficiency of a power transformer is of the order of 98 percent.

In a transformer routine efficiency depends upon?

Last Answer : In a transformer, routine efficiency depends upon load current and power factor of load.

An ideal transformer will have maximum efficiency at a load such that?

Last Answer : An ideal transformer will have maximum efficiency at a load such that copper loss equal to iron loss.

For a transformer, operating at constant load current, maximum efficiency will occur at?

Description : For a transformer, operating at constant load current, maximum efficiency will occur at?

Last Answer : For a transformer, operating at constant load current, maximum efficiency will occur at unity power factor.

The efficiency of a transformer, under heavy loads, is comparatively low because?

Description : The efficiency of a transformer, under heavy loads, is comparatively low because?

Last Answer : The efficiency of a transformer, under heavy loads, is comparatively low because copper loss becomes high in proportion to the output.

is efficiency of transformer is greater than electrical machine and why?

Last Answer : The efficiency of transformer is Greater than electrical Machine because there is no rotational losses in transformer and there is no air gap losses in transformer so losses is less in transformer compare to electrical machine so efficiency is higher in case of transformer.

when will be the maximum efficiency of transformer?

Last Answer : Transformer efficiency is maximum when copper losses are equal to iron losses.

Write selection criteria of distribution transformer with any four points.

Description : Write selection criteria of distribution transformer with any four points.

Last Answer : Selection Criteria for Distribution Transformer:  i) Ratings - The kVA ratings should comply with IS:2026 ( Part l )-1977*. The noload secondary voltage should be 433 volts for transformers to be ... is not necessary. vi) Cooling - The transformers covered in this group are generally ONAN, AN

In a power or distribution transformer about 10 percent end turns are heavily insulated?

Last Answer : In a power or distribution transformer about 10 percent end turns are heavily insulated to withstand the high voltage drop due to line surge produced by the shunting capacitance of the end turns.

Why the range of efficiency in transformers higher than those of other electrical machines?

Description : Why the range of efficiency in transformers higher than those of other electrical machines?

Last Answer : Transformers operate at higher efficiency when compared to other electrical machines.This is due to the absence of mechanical losses which is due to the absence of moving parts

What is the range of efficiency of transformers?

Description : What is the range of efficiency of transformers?

Last Answer : A:The efficiency of the transformer will be in the range of 94% to 99%. Among the available electrical machines the transformer has the highest efficiency

A 1:5 step-up transformer has 120V across the primary and 600 ohms resistance across the secondary. Assuming 100% efficiency, the primary current equals (A) 0.2 Amp. (B) 5 Amps. (C) 10 Amps. (D) 20 Amps.

Description : A 1:5 step-up transformer has 120V across the primary and 600 ohms resistance across the secondary. Assuming 100% efficiency, the primary current equals (A) 0.2 Amp. (B) 5 Amps. (C) 10 Amps. (D) 20 Amps.

Last Answer : I1= V1 /R1 = 120/600 = 0.2 (η = 100%, losses are zero ∴V1 = VR = I1R1)

What are the transformer losses?

Description : What are the transformer losses?

Last Answer : Answer: TRANSFORMER LOSSES - There are mainly two kinds of losses in a transformer namely 1. Copper loss (ohmic loss) and 2.magnetic loss (core loss). Copper losses are caused by the ... ohmic loss the following two losses are also present in the transformer stray load loss and dielectric loss.

What happen when Transformer is given DC supply ?

Description : What happen when Transformer is given DC supply ?

Last Answer : When DC supply is given to the transformer primary winding no back emf is induced in the transformer. Importance of Back emf is that it limits the current drawn by the machine. In the absence ... in burning down of primary winding. So when dc supply is given to transformer primary windings will burn

During No load why the power factor of the transformer is very low ?

Description : During No load why the power factor of the transformer is very low ?

Last Answer : Current flowing through the transformer consists of two components. Magnetizing current (Im) which is in quadrature (90 0 ) to the applied voltage and in phase current which is in phase to the applied voltage ... power factor of transformer during no load condition will by in the order of 0.1 to 0.2

What is the supply rated o/p if two single phase transformer connect to give three phase o/p from a three phase I/p?

Description : What is the supply rated o/p if two single phase transformer connect to give three phase o/p from a three phase I/p?

Last Answer : A. Each transformer is only capable of supplying 86.6%of its o/p rating

How to connect two single phase transformer to give three phase o/p from a three phase I/p ?

Description : How to connect two single phase transformer to give three phase o/p from a three phase I/p ?

Last Answer : A. They would have to connect in an open-delta.

What is the 3 ph transformer ?

Description : What is the 3 ph transformer ?

Last Answer : A. A 3ph transformer is that transformer which is equivalent to three single phase transformer but wound on one core and enclosed within one common case.

What parameters or technical particulars are important to be considered while designing protection scheme of the transformer?

Description : What parameters or technical particulars are important to be considered while designing protection scheme of the transformer?

Last Answer : 1.Network Diagram showing the position of the transformer in the system 2.kVA or MVA rating of the transformer 3.Fault Level at the transformer 4.Voltage Ratio 5.Winding Connections 6.Per Unit ... Oil Filled 11.Length and area of cross section of the connecting leads between CTs and Relay Panel

What can be the reasons for the failure of the transformer?

Description : What can be the reasons for the failure of the transformer?

Last Answer : Answer: Transformer is one of the most expensive equipments in the Power System. Failure of the transformer can cause outage of power supply for even days. However, multiple things can go wrong with ... relays. 3.Short Circuits 4.Open Circuits 5.Earth Faults 6.Over Voltage 7.Reduced system frequency

How Transformer Protection provided for internal faults?

Description : How Transformer Protection provided for internal faults?

Last Answer : 1.Bucholz Relay (1st Stage Alarm and 2nd Stage Trip) 2.Sudden Pressure Relay (1st Stage Alarm and 2nd Stage Trip) 3.Pressure Relief Valve (1st Stage Alarm and 2nd Stage Trip) 4.Pressure Switch ... 8.Gas Temperature Indicator (Alarm) 9.Silicon Breather (Passive - no alarm) 10.Smoke Detector (Alarm)

How does change in frequency affect the operation of a given transformer?

Description : How does change in frequency affect the operation of a given transformer?

Last Answer : a) Iron loss .........increases with a decrease in frequency. A 60-Hz transformer will have nearly 11% higher losses when worked on 50Hz instead of 60 Hz. However, when a 25-Hz ... ....since total loss is greater at a lower frequency, the temperature is increased with decrease in frequency.

Does the transformer draw any current when its secondary is open?

Description : Does the transformer draw any current when its secondary is open?

Last Answer : Yes, no-load primary current.

WHAT is ZIG ZAG Grounding Transformer

Description : WHAT is ZIG ZAG Grounding Transformer

Last Answer : ANSWER: Three Single Phase Transformers can be connected to have a three phase Zig Zag Transformer. This system can be used for either grounding or developing a fourth WIRE from a three phase neutral. An example ... - three phase - three wire system to a 480Y/277 V - three phase - four wire system

What is Meant by Temperature Rise in a Transformer?

Description : What is Meant by Temperature Rise in a Transformer?

Last Answer : ANSWER: Temperature rise in a transformer is the temper¬ature of the windings and insulation above the existing ambi¬ent or surrounding temperature, and is determined by the insulation class used in the transformer coils.

What is Meant by Regulation in a Transformer?

Description : What is Meant by Regulation in a Transformer?

Last Answer : ANSWER: Voltage regulation in transformers is the difference between the no load voltage and the full load voltage. This is usually expressed in terms of percentage. For example: A transformer delivers 100 ... from 2% to 4%, depending on the size and the application for which they are used

What is Polarity, When Associated With a Transformer?

Description : What is Polarity, When Associated With a Transformer?

Last Answer : A: Polarity is the instantaneous voltage obtained from the primary winding in relation to the secondary winding. Transformers 600 volts and below are normally connected in additive polarity - that ... parallel for three phase operations. Polarity is a term used only with single phase transformers

During No load why the power factor of the transformer is very low ?

Description : During No load why the power factor of the transformer is very low ?

Last Answer : A. Current flowing through the transformer consists of two components. Magnetizing current (Im) which is in quadrature (900) to the applied voltage and in phase current which is in phase to the applied voltage ... factor of transformer during no load condition will by in the order of 0.1 to 0.2

Explain about auto transformer?

Description : Explain about auto transformer?

Last Answer : A. It is type of transformer with only one winding a portion of which is shared by both primary and secondary. Advantages: It is used where transformation ratio differs little from unity. As ... voltage as per out requirements and can smoothly increase or decrease its value as per our requirement.

Explain about the open and short circuit tests on transformer?

Description : Explain about the open and short circuit tests on transformer?

Last Answer : A. Open circuit test (No load test) and short circuit test (full load test) are performed on a transformer to determine (i) Equivalent circuit of transformer (ii) Voltage ... determine copper loss in transformer at full load and parameters of approximate equivalent circuit of transformer.

EMF equation of the transformer?

Description : EMF equation of the transformer?

Last Answer : A. E = 4.44ΦmfN Volts. If E1 & E2 are primary and secondary emf’s and N1 & N2 are primary and secondary turns then, Voltage ratio= E1/E2 and Turns ratio of transformer = N1/N2 E1/E2 = N1/N2