Transformer
Input winding is called _____
Primary
If a single three-phase transformer of the proper ratings is not available, three-phase transformers can be connected to do the job. When this is done, the connection is called a(n)
Three-phase bank
An open delta connection is made using __ single-phase transformers.
2
A wye-delta transformer has a turns ratio of 2:1. It has a secondary line voltage of 480V. The secondary is connected to a wye-connected three-phase resistive load of 50 ohms in each phase. How much is the primary phase current?
A transformer tape wound core is assembled by?
Winding a long continuous tape of metal into a spiral
Primary Leads are labeled ____ and Secondary Leads are labeled ____
H, X
In calculating power in a three-phase circuit, the product of phase voltage and phase current and power factor are multiplied by?
3
Primary, secondary
A delta-connected three-phase alternator is driving a wye-connected resistive load. The alternator output voltage is 480V. The load resistors are 12 ohms each. What is the phase current in the alternator?
13.33A
Any transformer flux that does not follow the core and escapes into the surrounding air is called?
There is no separation between the Primary and Secondary in which transformer?
Autotransformer
The three-phase connection in which one end of each windings are connected together is called the __ connection
Wye
A delta-wye transformer has its __ connected as a delta and its __ connected as a wye.
Primary, secondary
A delta-connected set of windings has a phase current of 10A. The line current is?
17.32A
In three-phase power systems, the delivered power__
Never falls to zero
A 3 phase transformer of the proper ratings is not available, what can be used to do the job?
A 3 Phase Bank
Phase
A wye-delta transformer has a primary line voltage of 7200V and a secondary line voltage of 480 V. What is the the turns ratio?
8.66:1
A wye-delta transformer has a turns ratio of 2:1. It has a secondary line voltage of 480V. The secondary is connected to a wye-connected three-phase resistive load of 50 ohms in each phase. How much current flow is there in each load resistor?
5.54A
In a three-phase circuit, the true power (watts) is found by?
Multiplying apparent power by the power factor
A transformer with a "Main Transformer" and a "Teaser Transformer)
Hint: one is bigger than the other to supply single phase loads
T- Connected transformer
When single-phase loads are tied a __, the phase currents of the transformer will be automatically balanced.
Three-phase transformer
In an open delta with a center-tapped transformer. label the two ends of the center-tapped transformer as L2 and L3 and label the high leg as L1. The current flow in the neutral (center tap) is?
AN=A1+(A2 - A3)
A wye-connected alternator that has a phase voltages of 277V is feeding two loads. The first load is wye-connected inductors that have 40 ohms of XL. The second load is delta-connected capacitors that have XC of 60 ohms. How much is the alternator phase current?
6.93A
If a three-phase load is purely reactive, then the power calculated has units of __
VARs