The device for testing control transformers containing a three-phase power supply source with a first phase terminal (L1) and a neutral terminal (N) for a connection of a primary winding (1.1) of a control transformer to be tested; a measuring circuit having a ground bus and consisting of a voltmeter for a parallel connection to a secondary winding (1.2) of the control transformer to be tested, an ammeter and wattmeter , where the voltmeter is connected by its first terminal to the grounding bus of the measuring circuit, while the second terminal of the voltmeter is connected via the ammeter to the first terminal (8.1u) of the wattmeter voltage circuit and to the first terminal (8.1i) of the wattmeter current circuit while the second terminal (8.2u) of the wattmeter voltage circuit is connected to the grounding bus of the measuring circuit; a voltage recovery source and a circuit containing a compensating capacitor and a first adjustable resistor and the device for testing control transformers further containing a first regulating transformer , a second regulating transformer , an isolating transformer , a second adjustable resistor , a third adjustable resistor and a solid state relay , where the second terminal (8.2i) of the wattmeter current circuit is connected via the compensating capacitor to the first end of the first adjustable resistor , while the second end of the first adjustable resistor is connected to the second terminal of the output circuit of the voltage recovery source , where the first terminal of the output voltage recovery source is connected to the grounding bus of the measuring circuit, and where the first terminal of the input circuit of the voltage recovery source is connected to the neutral terminal (N) of the three-phase power supply source and the second terminal of the input circuit of the voltage recovery source is connected to the first phase terminal (L1) of the three-phase power supply source , while the second terminal of the output circuit of the voltage recovery source is further connected, together with the first end of the second adjustable resistor , to the first terminal (11.2a) of the secondary winding (11.2) of the isolating transformer , whose second terminal (11.2b) of the secondary winding (11.2) is connected to the first end of the third adjustable resistor , whose second end is connected, together with the second end of the second adjustable resistor , to the first terminal (13.a) of the solid state relay , which is connected by its second terminal to the second terminal (8.2i) of the current circuit of the wattmeter , while the second terminal (11.1b) of the primary winding (11.1) of the isolating transformer is connected to the slider of the first regulating transformer , whose winding is connected between the neutral terminal (N) of the three-phase power supply source and the second phase terminal (L2) of the three-phase power supply source ; and the first terminal (11.1a) of the primary winding (11.1) of the isolating transformer is connected to the slider of the second regulating transformer , whose winding is connected between the slider of the first regulating transformer and the third phase terminal (L3) of the three-phase power supply source , while the voltage recovery source is realized by an additional transformer (2.1) identical with the tested transformer , while the secondary winding of this additional transformer (2.1) forms the output circuit of the voltage recovery source and the primary winding (2.1.1) of the transformer (2.1) is connected to the output of the third regulating transformer (2.2), whose winding is connected as the input circuit of the voltage recovery source . <EOS>