The variable isolating transformzar RT 5 A is used to isolate instruments under test from the mains Power Supply The output voltage is continuously variable and this allows, for example, investigations into the behaviour of electrical or electronic instruments when supplied with over- or under supply voltages, checks of stabilizing circuits, precise setting of operation voltages and the connection of units, regardless of their supply voltage requirements. The transformer, therefore meet two important requiremznts for service work: Supply of an adjustable mains voltage with simultaneous protection against accident and damage.