TRANSFORMER TRAINER
The Transformer Trainer module fully examines single-phase and three-phase power and distribution transformers. The fully instrumented unit includes:
- One three-phase educational transformer
- Three single-phase educational transformers with tertiary windings
- One three-phase delta-star transformer
All windings of the educational transformers connect to colour-coded shrouded sockets on the control panel. The educational transformers work at one volt each turn, so the no-load output voltages are the same as the number of secondary turns.
An adjustable auto-transformer allows lower voltage experiments (for example - with the educational transformers). The module includes a second fixed ratio delta-star transformer for extra experiments.
The control panel includes all the analogue and digital meters and transducers needed to measure electrical voltage, current and power for all transformer tests. Also included are selectable resistive, inductive and capacitive loads, which can connect in parallel, series, delta or star connection.
Thermocouples are fixed to one set of windings and core of the three-phase educational transformer. They are also fixed to one of the single-phase educational transformers. The thermocouples connect to a digital temperature indicator to provide direct readings of core and winding temperatures.
For protection tests, the three-phase circuits include current transformers to link to an industrial standard protection relay. The user connects and sets the protection relay to detect line and earth currents, voltage and frequency faults. The relay also monitors and measures fault events and disturbances for fault analysis. The user sets the relay from its local control panel or by a cable link to a suitable computer and software (included). When the user applies a circuit fault, the relay opens circuit-breakers in the test circuits. The circuit-breakers also include hand-operated switches, and lamps. The lamps show whether the circuit-breakers are open or closed.
An extra socket on the equipment supplies power and control for any optional relays for use with the module, for example TecQuipment’s Differential Protection Relay (PSA15).
Supplied with the equipment is a set of shrouded leads for the user to connect the test circuits together. The unit includes an emergency switch, a mains supply isolator and protection fuses.
Learning outcomes
- Voltage and turns ratios
- Parallel and series windings, delta, star and interstar
- Open and short circuit tests to find transformer properties, including losses and efficiency
- Balanced and unbalanced loads
- Phase differences in popular three phase transformer connections
- Three to two-phase connections (Scott and Le Blanc)
- Core and winding temperatures in a three phase transformer (thermal tests)
- The effect of core-type construction in a three-phase transformer
- Differential protection of a delta-star connected transformer, when used with the Differential Protection Relay (PSA15)
