To determine the voltage regulation of synchronous generators, the direct load test is suitable only for alternators with power rating:

Voltage regulation of synchronous generators

Voltage regulation of synchronous generators refers to the ability of the generator to maintain a constant output voltage despite variations in load conditions or other external factors. 

The voltage regulation of the alternator can be defined as the change in terminal voltage from no-load to full-load rated value divided by the full-load rated voltage.

\(V.R.={E-V\over V}\)

Direct Load Test of alternators:

• The direct load test involves connecting the synchronous generator to a load and measuring the terminal voltage at different load levels (from no load to full load). By doing so, one can determine how the voltage varies with load and calculate the voltage regulation.
• This method requires the generator to be operated under its rated conditions, making it practical mainly for smaller generators with less than 5 kVA.
• For larger alternators (generators with a power rating greater than 100 kVA), the direct load test may not be practical due to the challenges associated with handling high power loads, safety concerns, and equipment limitations.
• Instead, larger generators often undergo open-circuit tests and short-circuit tests to determine their voltage regulation, as these methods do not require the generator to be connected to a load during the test.