Connection types
used to supply power to single phase and three phase loads, with 120v capabilities
Closed delta with center tap
what are three single-phase transformers called?
three phase bank
how do you find Ep in a delta?
Ep = EL
An open delta is assembled from two 69 kVA transformers, what is the total power output?
119.5 kVA
what does an orange wire indicate?
high leg
three phase power with only two transformers
open delta
transformers used in this connection must have two secondary windings that provide equal voltages. secondary windings are connected in such a manner that two delta connections are formed
double delta
An open delta is assembled from two 734 kVA transformers, what is the total power output?
1,271 kVA
how do you find your Load Ip ?
Load Ip = Ep/R
What is the formula for neutral current?
AN = A1 + (A2 - A3)
interconnected wye transformer is primarily used for grounding purposes, mainly used to establish a neutral point for the grounding of fault currents
Zig-Zag connections
this connection is three phase power into two phase power using two single phase transformers. the main transformer must have a center tap and the teaser must have a 86.6% tap on the primary side
Scott connection
what is the line voltage of a delta connection if the phase voltage is 286v
495.352v
a delta-delta connection has primary line voltage of 42069V and a secondary voltage 666V, with a delta connected load of 33ohms. what is the primary phase current?
Primary Ip = .32A
in three phase transformers connections, the primary leads are labeled as ____, and the secondary are labeled as _____.
H, X
this connection uses two transformers, one bing the main transformer and another called a teaser
T- connected transformer
metal stabilized coils are ____ within the core frame
pressure fitted
a delta-wye transformer has a a turns ratio of 69:1. it has a primary line voltage of 420. what is the secondary line voltage
Secondary Ep = 10.543
what is the turns ratio if the primary voltage is 300 and the secondary voltage is 6000
1:20
transformers shall not be connected as ____ unless the incoming power line contains a neutral conductors
wye-wye
but why?
this connection is preferred because it requires only one low voltage winding on each transformer.
Diametrical connection
before _____ , connections should be checked for proper polarity before making the final connection and applying power
closing a delta
a wye wye transformer has a turns ratio of 42:1. the secondary line voltage is 677V, with a delta connected load with 30ohms of resistance. what is the primary line current?
Primary IL = .931A
What is Z?
Load impedance
this % assumes a closed delta bank containing three transformers
57.7%