# If the percentage impedances of the two transformers working in parallel are different, then?

If the percentage impedances of the two transformers working in parallel are different, then?

If the percentage impedances of the two transformers working in parallel are different, then parallel operation will still be possible, but the power factors at which the two transformers operate will be different from the power factor of the common load.

## Related questions

Answer : Winding will be damaged

Description : Two transformers are connected in parallel. These transformers do not have equal percentage impedance. This is likely to result in?

Answer : Two transformers are connected in parallel. These transformers do not have equal percentage impedance. This is likely to result in loading of the transformers not in proportion to their kVA ratings.

Answer : Necessary conditions required to be satisfied in order to ensure successful parallel operation of single phase transformers:  1. Only transformers having the same phase displacement between primary and secondary ... . 7. The phase sequence must be followed strictly on HV and LV side connection.

Description : Two 3-phase transformers cannot be operated in parallel, if their :  (A) kVAs are different (B) phase sequences are different (C) % impedances are different (D) voltage ratios are different

Answer : Two 3-phase transformers cannot be operated in parallel, if their : phase sequences are different

Description : Two transformers with identical voltage ratings are working in parallel to supply common load. The percentage impedance of one transformer is higher compared to that of other. The load sharing ... respective impedance (4) Depend on the resistance to leakage reactance ratio of each transformer

Answer : Two transformers with identical voltage ratings are working in parallel to supply common load. The percentage impedance of one transformer is higher compared to that of other. The load sharing between the two transformer will: Be inversely proportional of their respective impedance

Description : Two transformers A and B having equal outputs and voltage ratios but unequal percentage impedances of 4 and 2 are operating in parallel. The transformer A will be overloaded by

Answer : Two transformers A and B having equal outputs and voltage ratios but unequal percentage impedances of 4 and 2 are operating in parallel. The transformer A will be overloaded by 33%

Description : The efficiency of two identical transformers under load conditions can be determined by?

Answer : The efficiency of two identical transformers under load conditions can be determined by back-to-back test.

Description : Losses which occur in rotating electric machines and do not occur in transformers are?

Answer : Friction losses windage losses

Answer : Distribution transformers are generally designed for maximum efficiency around 50% load.

Answer : Power transformers are generally designed to have maximum efficiency around near full-load.

Description : The efficiencies of transformers compared with that of electric motors of the same power are?

Answer : Transformers have high efficiency than the same ratted motors

Answer : Natural oil cooling is used for transformers up to a rating of 3000 kVA.

Answer : Short circuit test on transformers is conducted to determine copper losses.

Answer : Natural air cooling is generally restricted for transformers up to 1.5 MVA .

Description : An additional condition for parallel operation of three-phase transformers over single-phase transformers is that

Answer : An additional condition for parallel operation of three-phase transformers over single-phase transformers is that the transformers should belong to the same vector group

Description : In a transmission line if booster transformers are to be used, preferred location will be  (A) At the receiving end (B) At the sending end (C) At the intermediate point (D) Anywhere in the line

Answer : In a transmission line if booster transformers are to be used, preferred location will be At the intermediate point

Description : The friction losses in Real Transformers are :  (A) 0% (B) 5% (C) 25% (D) 50%

Answer : Current transformers (CT) : Current transformer (CT) actually step down the high current to low current for the operation of relays. Current transformer is use for measurement of ... use for relay. This is about potential transformer.

Description : Core type transformers are popular in___________.  (A) High voltage applications (B) Low voltage applications (C) All of the above (D) None of the above

Answer : Core type transformers are popular in High voltage applications

Answer : Instrument transformers are potential transformers, current transformers.

Description : State any two conditions for parallel operation of 3-phase transformer.

Answer : Conditions for Parallel operation of 3 phase transformer 1) Voltage ratings of both the transformers must be identical. 2) Percentage or p.u. impedance should be equal in magnitude. 3) X/R ratio ... between primary & secondary voltages must be same. 6) Phase sequence on both sides must be same.

Description : Which of the following is the advantage of using CRGO steel in transformers? A) High magnetic flux density B) Low permeability C) Both A and B D) None of these

Answer : It definitely High Magnetic Flux Density since a crgo steel has always a more around 3% of silicon proportion among the remaining ferrite which make cold rolled grain oriented steel having high flux magnetic ... for more about the crgo core you can learn here https://nicoreindia.com/crgo-core/

Description : What is the back EMF in Transformers?

Description : Classify the transformers based on the construction, frequency and power.

Answer : Classification of Transformer Based On: i) Construction: Shell type, Core type, Berry type ii) Change in voltage level: Step-Up, Step-Down, iii) Number of phases: Single phase, Three phase iv) ... Control vi) Cooling: Self-cooled, Air-cooled, Forced-air cooled, Oil-cooled, Forced-oil cooled.

Description : Which of the following connection of transformers will give highest value of secondary voltage ? (A) Delta primary delta secondary (B) Delta primary star secondary (C) Star primary star secondary (D) Star primary delta secondary

Answer : Which of the following connection of transformers will give highest value of secondary voltage ? (A) Delta primary delta secondary (B) Delta primary star secondary (C) Star primary star secondary (D) Star primary delta secondary

Description : Why do transformers make noise?

Answer : Transformers make noise based on it out put if an transformer outputs is 400v maximum than a 398v be apply to that transformer it also make a noise because of that

Description : Two transformers are to be operated in parallel such that they share load in proportion to their kVA ratings. The rating of the first transformer is 500 kVA ratings. The rating of the first transformer is 500 kVA and its pu ... its pu leakage impedance is  (A) 0.20 (B) 0.10 (C) 0.05 (D) 0.025

Answer : Two transformers are to be operated in parallel such that they share load in proportion to their kVA ratings. The rating of the first transformer is 500 kVA ratings. The rating of the first transformer is ... .05 pu. If the rating of second transformer is 250 kVA, its pu leakage impedance is 0.10

Answer : Harmonics in transformer result in increased core losses, increased I2R losses, and magnetic interference with communication circuits.

Answer : A common method of cooling a power transformer is oil cooling.

Description : Two transformers operating in parallel will share the load depending upon their

Answer : Two transformers operating in parallel will share the load depending upon their Per unit impedance

Description : When two transformer of different kVA rating are connected in parallel they share the load in proportion to their respective kVA rating only when their:

Answer : When two transformer of different kVA rating are connected in parallel they share the load in proportion to their respective kVA rating only when their: P u impedance are equal

Description : If two 3-phase transformers with unequal voltage ratios are connected in parallel, the result is (A) circulating current on no-load (B) no circulating current on no-load (C) dead short-circuit (D) equal no-load secondary emfs

Description : State any two applications of single phase autotransformer.

Answer : Applications of single phase auto transformers: 1) Give small boost to distribution cable to correct the voltage drop. 2) As auto transformer starter for induction motors. 3) As furnace supply ... . 5) In control equipment for single phase locomotives. 6) As dimmer in lighting circuits.

Description : Why circuit breaker connect b)w two transformer  (same rating

Answer : Because two transformers connection is in parallel to share the load if any transformer is receives the surge current because of the fault so to protect the other transformer from the fault.

Description : For a transmission line open circuit and short circuit impedances are 20 Ω and 5 Ω. Then characteristic impedance is: (1) 100 Ω (2) 50 Ω (3) 25 Ω (4) 10 Ω

Answer : For a transmission line open circuit and short circuit impedances are 20 Ω and 5 Ω. Then characteristic impedance is: 10 Ω

Description : Define transformation ratio in terms of current and voltage.

Answer : (i) Transformation Ratio (K) is defined as the ratio of the primary current to the secondary current.  (ii) Transformation Ratio (K) is defined as the ratio of the secondary voltage to the primary voltage.

Description : Compare core type transformer and shell type transformer on the following parameters. (i) Types of winding used, (ii) Application

Description : Define: (i) Commercial efficiency of a transformer and  (ii) All day efficiency of a transformer.

Answer : (i) Commercial Efficiency : It is the ratio of output power in watt to the input power in watt. (ii) All day efficiency of a transformer: It is the ratio of output energy in kWh to the input energy in kWh in the 24 hours of the day

Description : A 50 KVA transformer has iron loss 2 kW on full load. Calculate its iron loss at 75% of full load.

Answer : Iron loss is dependent on voltage and independent of load. Hence iron loss at 75% of Load = Iron loss at full load = 2 kW

Description : State any four properties of Ideal transformer.

Answer : Properties of Ideal transformer: 1) No losses (iron and copper losses), hence no temperature rise. 2) No magnetic leakage i.e (Coefficient of coupling between primary and secondary windings is unity) 3) Zero winding ... drop i.e. E1 = V1, E2 = V2 5) Efficiency 100 %. 6) Regulation 0 %.

Description : Draw the connection diagram of long shunt differential D.C. compound generator.

Description : State and justify which of the following two transformers is better:  Transformer A = 4% voltage regulation  Transformer B = 6% voltage regulation

Answer : Transformer A with 4% voltage regulation is better.  Justification: Voltage regulation refers to the percentage change in secondary voltage when load is changed from no-load to full-load with primary voltage ... 4% voltage regulation, which is less as compared to 6% of transformer B, it is better.

Description : Two transformers having the same p.u. impedance connected in parallel share the connected load (A) equally (B) in proportion to the respective ratings (C) in proportion to the voltage ratio (D) in proportion to the zero phase displacement

Answer : Two transformers having the same p.u. impedance connected in parallel share the connected load in proportion to the respective ratings

Description : Three equal impedances are first connected in delta across a 3 -phase balanced supply. If the same impedances are connected in star across the same supply then,

Answer : If two parallel-connected resistors dissipate 6 watts and 10 watts of power, then 16 watts is the total power loss.

Description : Which of the following are constant losses in Transformers? (1) Winding losses (2) Core losses (3) Both Winding & core losses (4) None of these

Answer : Which of the following are constant losses in Transformers? (1) Winding losses (2) Core losses (3) Both Winding & core losses (4) None of these

Description : Instruments transformers are used on a.c. circuits for extending the range of (a) ammeters (b) voltmeters (c) wattmeters (d) all of these