I have not used that particular make/model, but my comments will apply to all stabilizers using tap-switching to regulate the AC voltage.
1) The transformer in a tap-switching stabilizer has multiple taps in the winding.
2) The number of relays inside the stabilizer depends upon how many taps the transformer has.
3) Since taps are at fixed number of turns, so don't expect a tight output regulation.
For example, consider a stabilizer that has been designed to provide regulated 220V from input (160-250V). Now this range of 250-160 = 90V should have multiple taps. The greater the number of taps in this 90V range, the better output regulation you will have. Generally the taps spaced at 10-15V provide optimum regulation. With 15V tap spacing and a good control circuit, you will have +7.5 to -7.5 Volt error (output will remain in 212 - 227V range)
In your case, what I can understand is that your stabilizer can boost the voltage by maximum 30V (because when you have 165V input, you get 195V output and when you have 200V input, the output becomes 230V)
Mostly stabilizers available in market have just two relays inside which can accommodate a maximum 3 taps. If we take one tap for 250V input, then on lower voltage side, you have 2 taps left. This is the simplest but worst design.
If you have any more question, please feel free to ask.