Direct, Indirect and Regenerative Type of Testing on Machine

Sr. No

Point  Of
comparison

Indirect Test

Direct Test

Regenerative Test

1

Loading Method

It is a not load indirect test.

It is a direct load test.

It is an indirect back to back or
regenerative test.

2

Power required

Small (Equal to No load losses)

More  (Equal to output +losses)

Medium   (Some power is fed back from the
generator.

3

Suitability

Suitable for shunt machine and large
capacity machine.

Suitable for small machine up to 5Kw capacity.

Suitable for two identical
small/medium/Big machines.

4

Commutation

Cannot be a observed machine runs on
no-load.

Can be observed as machine is fully
loaded.

Can be observed as machine carries
full load currents.

5

Temperature rise

Cannot be a observed machine runs on
no-load.

Can be observed as machine is fully
loaded.

Can 
be observed as machine carry full load currents.

6

Limitations

Suitable for only shunt machine and
level compound machine.

Suitable for any type of machine

Suitable for two identical machine

7

Accuracy in result

Results are approximate.

Results are most accurate.

Results are nearly accurate.