2-2 study guide
Between the replaceable fuse and the primary coil
An isolation link or current limiting fuse, in an underground transformer is ?
Increases by 1% for each degree
As the temperature drops below 30C a transformer kVA rating ?
Phase angle
Graphical illustrations using vectors can easily show the following transformer qualities, Transformer output voltages have magnitude, direction , phase sequence, and ?
Operated while the transformer is energized
If a Transformer is equipped with a taps changer, it must never be ?
A Balanced load
If a load test was done on a transformer and the load an A-conductor was the same as the load on B-conductor, the condition would be referred to as ?
Back feed the one with the blown fuse
If two transformers are connected in parallel and a primary fuse blows on one of the transformers, the transformer will ?
Connect the coils in parallel
If you have installed several 120 volt security lights and need the total capacity of the transformer , you should ?
Reopen
If you hold a CSP's handle in the "C" position on a permanent fault, the secondary breaker will
Left side when facing the secondaryd
Industry standards for electrical transformers call for the H1 terminal to be located on the?
On full winding (100%)
The electrical worker installing the transformer should check the tap changer position before its put into service. Unless otherwise instructed, the tap setting must always be placed ?
Wheel
The electrical worker who is familiar with the vector ? Can plot out any 3 - phase system in 30 degree increments.
Completely self protected
The initials CSP on a transformer mean?
Insulation
The 4 internal parts of a distribution transformer are primary windings,secondary windings, iron core, and ?
Inside of the tank
The H2 terminal on a single bushing transformer is solidly connected to the ?
Shielded
A voltage indicator may NOT detect the presence of voltage in a wire that is ?
Current limiting fuse
A ? Reduces the risk of violent transformer failure when it is in series with cutout
Turns ratio
A Transformer equipped with taps changes the ? Of the secondary output
120v
A Transformer is rated at 7200/12470- 120/240. If you Parallel the secondary coils AC,BD full amperage capacity is available at ?
22.38 kva
A spot load check on a transformer finds ; A lead with 110 volts and 105 amperes, B lead with 114 volts and 95 amperes. What is the exact KVA being taken off the transformer ?
Megohmeter
A test instrument that is used to test for insulation breakdown is ?
Number of turns in each coil
A transformer changes the voltage and current from one level to another because of the ?
5%
A transformer that is energized but under no load can draw as much as ? Of the current taken in by a loaded transformer of the same size
Core and coil assembly
A typical distribution transformer consists of a(n) ?
The time of day when the load is considered at the highest peak
Clip on ammeter test should be take during ?
1000
Kilovolt-ampere being drawn off a transformer can be found by multiplying secondary voltage times secondary amperage and then dividing by ?
Full load output
Kva rating of a transformer represents ?
Person who installed it
Lockout/Tagout is normally removed by the ? Other than in an emergency situation
Square and rectangle
Medium and large size transformers use ? Type wire for more compact and solidly built coil which also provides better conductivity for the heat to flow out of the windings
High current unbalances
One problem with small 3-phase voltage unbalances is that they can cause ?
Install bushing covers
One requirement of the 1996 migratory bird treaty act regarding new transformers installations to protect birds from electrocution
Marked with a white dot near H1 and X1 on the transformer case
Polarity test should be performed on a tranformer with a missing or damaged name plate and the polarity
Secondary output voltage
Primary voltage can be determined by multiplying tranformer turns ratio by the ?
Magnitude
The length of a vector line is proportional to the ?
Overcurrent
The main reason meter fuses blow ( when the meter has fuses) is ?
14,400 x 7200 - 120/240
The most common dual voltage distribution transformer is rated at ?
When a utility has 2 different distribution voltages
The most common use of a dual voltage transformer is ?
Looping prevents water from getting into the connection
The purpose of forming a loop in the transformer lead and inserting the lead into the top terminal is the ?
208
The secondary amperage available on a 25 kva tranformer at 120 v is
Number of turns in the winding
The strength of an electromagnetic field in a transformer is dependent on the ease of which the core is magnetized the amount of current flowing and the ?
1200 v
The transformer ratio is 10:1. The secondary voltage is 120 v and the primary voltage is?
Basic impulse
The voltage level that can flashover the outside of equipment, such as an insulator, is called the ? Level
E x I ——— 1000
To determine the power being drawn from a transformer , use a multi meter to find the voltage across and the current through the secondary coils. With these values and the formula kVA=?, A spot check of transformer power will be found.
Fixed reference
To vector a 3-phase system, it is essential to establish a ? Of the phases
Impedance
When paralleling two transformers, the ? Of the 2 transformers must be within 107.5% to 92.5% of each other
Lower than
When performing a polarity test on a single phase transformer, the voltmeter reading on a subtractive transformer will be ? The source voltage
Greater measuring capability
When using test instruments, the main reason for the increase in the use of digital electronic technology is ?
The primary lead be taken off the line
When working on a CSP transformer, it is highly recommended that before work is performed on a de energized secondary ?
2
While inspecting a transformer prior to installation, if there is a slash (/) between the primary voltages, the transformer should have ? Primary bushing(s) and is suitable for a delta primary connection
Will not de energize the primary lead from the transformer to the line
With a CSP transformer , the primary fuse link
Removing the grounding straps connecting the secondary in series , and paralleling the primary side
You can get 480 volts out of two 120/240 volt transformers by ?
