Transformers Week 2 Questions Flashcards
A name plate reads- 7200/12470Y how do I connect this to a 7200/12470 system?
WYE- Phase to Ground
A name plate reads- 7200/12470Y how do I connect this to a 4160/7200 system?
Delta- Phase to Phase
If a name plate lists 2 primary numbers separated by a / which is the primary coil rating?
The smaller of the 2 numbers
A nameplate reads 12470GRDY/7200. How many primary bushings does this transformer have?
One, H1. the H2 is the tank ground and it’s a WYE only connection
Engineers can choose from 3 different primary voltage designations when buying transformers, what are they?
WYE Only, WYE and DELTA, DELTA only
If a transformer nameplate has only one number listed for a primary voltage rating, how should it be connected?
DELTA = Phase to Phase
What information would you typically reference the nameplate for?
Voltage Ratings, KVA, Serial Number, Polarity, Impedance, Weight
Why is it important to perform a continuity test on a transformer before installation?
To test for a faulty transformer
What must be done before connecting the customers load?
Check Secondary Voltage at meter socket
When you perform a continuity test on a transformer and you hear a beep when reading between H1 and X1, what does that mean?
It’s a Faulty Transformer, connection between high and low side means bad transformer
A nameplate reads 12470GRDY/7200 volts. How would it connect to a 4160/7200-volt system?
Can Not connect, can only connect transformer to WYE system
What is a tap changer used for on a transformer?
To Change the secondary voltage output by changing the windings on the primary coil. Do not operate energized, Raises or lowers secondary voltage by 2.5% or 4.5%
What is polarity?
The direction of power flow, Subtractive and Additive
What is impedance?
Total Opposition to current Flow, Efficiency of the transformer
What is a dual voltage switch and when can I operate it?
The transformer has two primary coil voltages example (7200/14400) do not operate energized (dual rated)
What is a Megger Tester?
Tests for coil insulation damage
System Voltage is 2400/4160 how do I connect to a 4160/7200Y Transformer?
Delta
What are the 3 name plate connections?
- Delta- One Number ex. 7200
- WYE/DELTA- Two Numbers ex. 7200/12470Y. Use smallest Number to connect
- WYE- 12470GRDY/7200 Single bushing WYE only
Can I connect a dual bushing transformer WYE or Phase to Ground?
Yes, if the smaller number of name plate matches the phase to ground of transformer
In WYE connection where are the H1 and the H2 Bushings connected?
H1 to Primary and H2 to Ground
In a DELTA system how are the H1 and H2 Bushings Connected?
H1 and H2 connect to Primary
How do I connect a 7200GRDY/12470 transformer to 7200/12470-volt line?
Can’t connect- fake news
