Specialty transformers level 4 module 6

Large transformers used in transmission systems are called

Power transformers.

When the secondaries are wye connected,

They have a common wye point (N) and the secondary line voltages are 1.732 times the phase voltage.

Many special step down transformers are used for small work, such as doorbells or other signaling systems, battery charging rectifiers, and

Individual low voltage lamps.

One common type of transformer is a single phase transformer with

Two secondaries.

For autotransformers ? The primary voltage is applied to the primary or

Common winding.

For autotransformers, the secondary or series winding is connected in series with the

Primary at the junction terminal.

step voltage down and

Current goes up.

Step voltage up and

Current goes down.

Burden refers to the total load seen by the

Current transformer secondary.

The voltage across the secondary terminals of the potential transformer is always

Lower than the primary voltage and is rated at 120V.

In a three phase, four wire system, the neutral conductor can be severely affected by

Nonlinear loads connected to the 120V branch circuits.

If the resonant frequency is near that of the harmonic voltage, the resultant harmonic current can increase substantially,

Overloading the the capacitors and blowing the capacitor fuses.

Neutral busbars and connecting lugs are sized to carry the

Full value of the rated phase current.

When surveying for harmonics, neutral overloading in receptacle branch circuits can sometimes be detected by

Measuring the neutral to ground voltage at the receptacle.

The crest factor of a waveform is the ratio of the

Peak value to the rms value.

The triplen harmonics neutral current can be reduced by

Adding harmonic filters at the load.