DOUBLE FREQUENCY DOUBLE VOLTAGE TEST SET This test set provides a continuously variable output voltage at double frequency to test the insulation between turns of coils, layer to layer, terminals of windings with either uniform or graded insulation and also between the windings and earth, with graded insulation of both Distribution and Power transformers. An alternating voltage of sine wave form (as much as possible) at double frequency (100 Hz.) and double in amplitude can be applied at one side of the transformer under test while the windings, which are not connected to the source of excitation, are left on open circuit. This higher frequency is considered to avoid excessive excitation current during the testing. Voltage source: To generate a voltage at 100 Hz., one 3-phase squirrel cage induction motor is given a supply through a star-delta switch. This motor drives the slip ring induction motor (generator). A variable voltage is also supplied to the generator thereby producing double frequency, which along with the output voltage of the generator is available across the terminals of the Set. Selection chart: Type Output capacity of generator(slip-ring motor) In HP Output capacity of generator(slip-ring motor) In kW Suitable to test transformer upto dfdv010h 10HP 7.5KW 250KVA dfdv020h 20HP 15 KW 750KVA dfdv025h 25HP 18.75KW 1MVA dfdv030h 30HP 22.5KW 2MVA dfdv040h 40HP 30KW 3MVA dfdv050h 50HP 37.5KW 4MVA dfdv060h 60HP 45KW 5MVA dfdv080h 80HP 60KW 6MVA dfdv100H 100HP 75KW 7.5MVA dfdv150h 150HP 112.5KW 11.2MVA Qty :