Question 1
A 75 kVA, 600 V to 120/208 V three-phase transformer supplies a panelboard. What is the approximate full-load current on the 120/208 V secondary?
Question 2
A 600V to 120/208V transformer has a kVA rating of 45 kVA. What is the maximum calculated line current available on the secondary side?
Question 3
A 100 kVA transformer has a primary voltage of 600V and secondary of 240V. If the transformer is 98% efficient, what is the input power at full load?
Question 4
A 3-phase Delta-Wye transformer has a primary voltage of 4160V and a secondary voltage of 600/347V. What is the turns ratio?
Question 5
What is the calculated primary current for a 75 kVA, 600V to 208/120V 3-phase transformer?
Question 6
A 10 kVA 600V/120V single-phase transformer is fully loaded. What is the approximate current on the primary side?
Question 7
A 75 kVA transformer has a 600V primary and a 120/208V secondary. If the transformer is operating at 80% of its rated capacity, what is the current in the secondary line conductors?
Question 8
A 10 kVA, 600V/120V single-phase transformer is fully loaded. What is the approximate current on the primary side?
Question 9
A 75 kVA transformer has a 600V primary and a 120/208V secondary. What is the rated full-load current on the secondary side?
Question 10
An electrician is calculating the line current for a 208V, 3-phase, 45 kVA transformer secondary. What is the approximate line current at full load?
Question 11
A 10 kVA, 600V to 120/208V 3-phase transformer is being installed. What is the rated line current on the primary side?
Question 12
A 3-phase transformer bank consists of three 25 kVA single-phase transformers connected in a Wye-Delta configuration. What is the total kVA rating of the bank and the secondary line current if the secondary voltage is 240V?
Question 13
What is the calculated line current for a 3-phase, 45 kVA transformer secondary operating at 208V?
Question 14
A 240 V single-phase motor draws 12 A at full load. Approximately what size (in kVA) is the load?
Question 15
A 45 kVA, 600 V to 208/120 V three-phase transformer supplies a panelboard. The calculated continuous load on the secondary is 120 A. What is the minimum ampere rating of the secondary overcurrent device, assuming Canadian requirements for continuous loading on transformers?
Question 16
An electrician is installing a control circuit for a motor starter using a control transformer. Which practice is MOST important for safety and proper operation?
Question 17
Calculate the primary full-load current of a 75 kVA, 480V, 3-phase transformer.
Question 18
A transformer has 500 turns on the primary and 100 turns on the secondary. If the primary voltage is 240V, what is the secondary voltage?
Question 19
Calculate the kVA rating of a transformer required to serve a 480V, 3-phase load drawing 50A.
Question 20
A 480V to 120V step-down transformer has a turns ratio of 4:1. If the secondary current is 20A, what is the primary current (neglecting losses)?
Question 21
Calculate the secondary amps of a transformer rated 75 kVA, 480V primary / 208V 3-phase secondary.
Question 22
When sizing a transformer, 1 kVA is equal to how many VA?