A turns ratio meter may be connected to each phase of each set of windings. The excitation voltage used in testing is a DC square wave. The excitation voltage is relatively low, between 1 and 48 volts. The step down and step up testing is performed several times with different voltages and/or frequencies. Excitation losses of the transformer are determined based upon the multiple step down and step up tests. The step down and step up testing can be performed without reconfiguring the test leads on the transformer. The testing is performed on a single phase of the transformer or all three phases of the transformer simultaneously. The turns ratio of the transformer is accurately determined using the results of the step down and step up testing and the calculated excitation losses.

A monitoring system includes an array of optical sensors disposed within a transformer tank. Each optical sensor is configured to have an optical output that changes in response to a temperature within the transformer tank. An analyzer is coupled to the array of optical sensors. The analyzer is configured to determine a sensed temperature distribution based on the sensed temperature. The sensed temperature distribution is compared to an expected distribution. Exterior contamination of the transformer tank is detected based on the comparison.

A testing device for an apparatus of an energy system which has inputs that can be connected in a conductive manner to at least one current transformer and at least one voltage transformer. The testing device is designed to apply a first test signal to a secondary side of the voltage transformer and, at the same time, to apply a second test signal to a primary side of the current transformer.

To ascertain a parameter of a transformer (40) that has a high voltage side (41) and a low voltage side (43), a test signal generated by a source (13) is impressed on the low voltage side (43). A test response of the transformer (40) is recorded. A leakage reactance and/or a leakage inductance of the transformer (40) is determined by an evaluation device (18) of an apparatus (10) on the basis of the test response of the transformer (40).

To ascertain a parameter of a transformer (40) that has a high voltage side (41) and a low voltage side (43), a test signal generated by a source (13) is impressed on the low voltage side (43). A test response of the transformer (40) is recorded. A leakage reactance and/or a leakage inductance of the transformer (40) is determined by an evaluation device (18) of an apparatus (10) on the basis of the test response of the transformer (40).

A mobile transformer test device (10) for testing a power transformer (40) has connectors (12) for the detachable connection of the transformer test device (10) to the power transformer (40). The transformer test device (10) has a source (5) for generating a test signal. The mobile transformer test device (10) has an evaluation circuit (6) for determining, based on the test signal and a test response of the power transformer (40), information regarding a B-H curve (50, 60) of the power transformer (40).

A switch apparatus (10) for a measuring device (30) for a transformer includes controllable switch device (14) which are configured to short-circuit respectively assigned terminals (11) of one of a plurality of windings of the transformer. A test apparatus (40) including the switch apparatus (10) and a method (50) for operating the switch apparatus (10) are also disclosed. With apparatuses (10, 40) and methods (50) according to the exemplary embodiments, the work effort, time expenditure and errors and inaccuracies can be reduced through an automated testing of transformers.

A device including at least two transfomers, wherein: each winding of a transformer is electrically in series with a winding of another transformer, and the transformers have a transformation ratio different from one.

A device including at least two transfomers, wherein: each winding of a transformer is electrically in series with a winding of another transformer, and the transformers have a transformation ratio different from one.

A method for performing diagnostics on a target transformer includes applying a voltage output of a voltage generator to a winding or phase of the target transformer; controlling the voltage generator to output an AC voltage at a first frequency and then a second frequency and measuring first and second excitation currents flowing into the target transformer associated with the first frequency and second frequency, respectively. The method further includes determining an actual excitation current of the target transformer as a function of both the first and second excitation currents, and comparing the actual excitation current of the target transformer to excitation currents associated with one or more benchmark transformers having known electrical characteristics. And when the actual excitation current of the target transformer matches an excitation current of one of benchmark transformers, determining the electrical characteristics of the target transformer to match electrical characteristics of the one benchmark transformer.