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## Why do we need of earthing if source is Delta connected isolated star connected?

to assure correct operation of electrical and sensitive equipment by providing an absolute ‘earth’ reference voltage value; to dissipate the energy from direct or indirect lightning strikes; other advantages are given in ‘Advanced Electrical Services Engineering’ which can be obtained from CIBSE bookshop – Link.

## What is effect of star Delta Connection in transformer design?

Advantages of Star Delta Connection The primary side is star connected. Hence fewer numbers of turns are required. This makes the connection economical for large high voltage step down power transformers. The neutral available on the primary can be earthed to avoid distortion.

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## Is a delta system grounded?

The delta system can also be grounded, as shown in Figure 2 below. Compared with the solidly-grounded wye system of Figure 1 this system grounding arrangement has a number of disadvantages. The phase-to-ground voltages are not equal, and therefore the system is not suitable for single-phase loads.

## Why is the transformer star point grounded to ground?

The transformer star point is grounded to get the earth fault protection. The unbalance current in the phases will pass through the neutral to ground. The single phase supply can be obtained by grounding the neutral of the transformer.

## Can a star star transformer be used in parallel with a Delta Delta transformer?

In this type of connection, the secondary voltage is not in phase with the primary. Hence it is not possible to operate this connection in parallel with star-star or delta-delta connected transformer. One problem associated with this connection is that the secondary voltage is shifted by 30 0 with respect to the primary voltage.

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## What happens when a transformer neutral is earthed?

The system has to have good insulation, as the voltage on the star point and the healthy phases will rise while the fault is operating. Where the star point is solidly earthed, the voltage will remain stable (apart from the faulty phase).

## Are there any problems with a star Delta Connection?

One problem associated with this connection is that the secondary voltage is shifted by 300 with respect to the primary voltage. This can cause problems when paralleling 3-phase transformers since transformers secondary voltages must be in-phase to be paralleled. Therefore, we must pay attention to these shifts.