Voltage increase after a 100 meter cable?

Hi all 

So in one project we have an MDB that with a voltage of L1 : 243 L2 : 245 L3 : 243 , these values are normal in my country but the problem is that in the SDB that is around 100 meters away with around 4.5% voltage drop ( the schools electrician knew what he was doing apparently ) and the voltage at the SDB is L1 : 246 L2 : 250 L3 : 247 , i am a bit confused is why the voltage increased where the voltage drop is high and should be lower at the SDB than the MDB . 

iceng4 months ago

He used a simple adder transformer at the beginning or end of the 100m cable...

Not nearly as expensive as a variac...