current transformer rating. what is the purpose of 5A secondary current rating for a Current transformer?...
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current transformer rating. what is the purpose of 5A secondary
current rating for a Current transformer?...
1. Calculate the VA output required from a current transformer of 5A rated secondary current when...
1. Calculate the VA output required from a current transformer of 5A rated secondary current when the burden consists of relays requiring 10VA at 5A plus a loop lead resistance of 0.8 ohms. 2. What output VA would be required from a current transformer of 1A rated secondary current for a burden of 10VA at 1A plus lead resistance as in part 1. 3. An earth fault relay has a burden of 1VA at setting and is set at 0.2A....
A generator transformer has a magnetising current of 1.5 %. The primary winding voltage is 27 kV and the secondary voltage is 330kV. The transformer rating is 360 MVA. What is the allowable operating...
A generator transformer has a magnetising current of 1.5 %. The primary winding voltage is 27 kV and the secondary voltage is 330kV. The transformer rating is 360 MVA. What is the allowable operating current differential, in terms of Amperes on the primary, that should not cause the protection to operate? Select one: a. 200.00 Amperes b. 31.08 Amperes c. 115.47 Amperes d. 66.00 Amperes
1. A step down transformer with a turns ratio of 6 to 1 has 120V applied...
1. A step down transformer with a turns ratio of 6 to 1 has 120V applied to its primary coil. A 25Ω load resistor is connected to the secondary coil. Calculate the following (3+2+2 -7 Points) Secondary coil voltage Secondary coil current Primary coil current a. b. c. 2. A step up transformer has a primary coil current of 1SA and an applied voltage of 220V. The secondary coil current is 5A. Calculate the following (3+3+2+2-10 Points) Secondary coil voltage...
A three-phase Yy0 connected transformer has a nominal rating of 250 kVA and a voltage ratio...
A three-phase Yy0 connected transformer has a nominal rating of 250 kVA and a voltage ratio 15:0.4 kV. After conducting the short-circuit test, where the secondary winding is short-circuited, it is found that the primary series resistance is 0.08 pu and the primary series impedance magnitude is 0.1pu. The effect of the parallel branch in the transformer’s equivalent circuit may be neglected. Explain what information ‘Yy0’ gives about the transformer. Draw the per-phase equivalent circuit of the transformer during the...
1. Is there direct contact between the primary and secondary coils in a transformer? 2. Why...
1. Is there direct contact between the primary and secondary coils in a transformer? 2. Why does the coil in a DC motor turn? Compare that to the means by which a generator produces current 3. Why are only a few types of atoms (iron, for example) magnetic?
1. (a) State briefly the consequences of opening the secondary of a current transformer when it...
1. (a) State briefly the consequences of opening the secondary of a current transformer when it is in service. State the precaution to be taken should disconnection be necessary. (b) A CT has a current ratio of 100/1. If the primary load current is 100 A, determine the excitation current, the maximum ratio error and the maximum phase angle error if the burden is 5 ohms. The CT characteristic gives an excitation current of 0.014 A for a secondary voltage...
A 5 KVA, 480/120V, 60 Hz, non-ideal transformer has the following primary and secondary resistance and...
A 5 KVA, 480/120V, 60 Hz, non-ideal transformer has the following primary and secondary resistance and reactance values R 80,X1-12Q, R 0.15Q, X 0.20, R 18 KQ, and X 15 KO If the transformer is operating at 90% of its rated load current and the voltage is leading the current by 40 degree: a) Draw the approximate equivalent circuit of the transformer referred to secondary side, b) Calculate the efficiency of the transformer, and c) The voltage regulation
Question I The rating of a three phase three winding transformer are: Y-connected 10 KV 40 MVA Secondary Y-connecte...
Question I The rating of a three phase three winding transformer are: Y-connected 10 KV 40 MVA Secondary Y-connected 22 KV 40 MVA A-connected 4 KV 15 MVA Primary Tertiary Neglecting winding resistance and exciting current, the per unit leakage reactance are: Mps 9.6 % pu on 40 MVA, 11022 KV xm = 7.2 % pu on 40 MVA, I 10/ 4 KV Xsti: 12 % pu on 40 MVA, 22/ 4 KV Determine the era nyimpedances of the transformer...
1. In order to meet an emergency, three single-phase transformers with 12.470/7.200 V are connected in...
1. In order to meet an emergency, three single-phase transformers with 12.470/7.200 V are connected in Delta-Wye to form a three-phase transformer which is fed by a 12.470 V transmission line. If the transformer supplies 60 MVA to a load, calculate: (3 marks) a. The turns ratio for each transformer b. The currents in the primary and secondary windings of the transformer c. The primary and secondary transmission line currents 2. A Wye-Delta transformer is connected to a 66 kV...
d) Consider an ideal, single-phase 2400V-240V transformer. The primary is connected to a 2200V source and...
d) Consider an ideal, single-phase 2400V-240V transformer. The
primary is connected to a 2200V source and the secondary is
connected to an impedance of 2Ω ∠36.9o , find all the values in
Table 1.
Table 1
No
Parameters
1
The secondary output current and voltage.
2
The primary input current
3
The load impedance as seen from the primary side.
4
The input and output apparent power
5
The output power factor
e) A 30MVA 33/11 kV star-delta three phase...
1. A step down transformer with a turns ratio of 6 to 1 has 120V applied to its primary coil. A 25Ω load resistor is connected to the secondary coil. Calculate the following (3+2+2 -7 Points) Secondary coil voltage Secondary coil current Primary coil current a. b. c. 2. A step up transformer has a primary coil current of 1SA and an applied voltage of 220V. The secondary coil current is 5A. Calculate the following (3+3+2+2-10 Points) Secondary coil voltage...
A 5 KVA, 480/120V, 60 Hz, non-ideal transformer has the following primary and secondary resistance and reactance values R 80,X1-12Q, R 0.15Q, X 0.20, R 18 KQ, and X 15 KO If the transformer is operating at 90% of its rated load current and the voltage is leading the current by 40 degree: a) Draw the approximate equivalent circuit of the transformer referred to secondary side, b) Calculate the efficiency of the transformer, and c) The voltage regulation
Question I The rating of a three phase three winding transformer are: Y-connected 10 KV 40 MVA Secondary Y-connected 22 KV 40 MVA A-connected 4 KV 15 MVA Primary Tertiary Neglecting winding resistance and exciting current, the per unit leakage reactance are: Mps 9.6 % pu on 40 MVA, 11022 KV xm = 7.2 % pu on 40 MVA, I 10/ 4 KV Xsti: 12 % pu on 40 MVA, 22/ 4 KV Determine the era nyimpedances of the transformer...
1. In order to meet an emergency, three single-phase transformers with 12.470/7.200 V are connected in Delta-Wye to form a three-phase transformer which is fed by a 12.470 V transmission line. If the transformer supplies 60 MVA to a load, calculate: (3 marks) a. The turns ratio for each transformer b. The currents in the primary and secondary windings of the transformer c. The primary and secondary transmission line currents 2. A Wye-Delta transformer is connected to a 66 kV...
d) Consider an ideal, single-phase 2400V-240V transformer. The
primary is connected to a 2200V source and the secondary is
connected to an impedance of 2Ω ∠36.9o , find all the values in
Table 1.
Table 1
No
Parameters
1
The secondary output current and voltage.
2
The primary input current
3
The load impedance as seen from the primary side.
4
The input and output apparent power
5
The output power factor
e) A 30MVA 33/11 kV star-delta three phase...
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