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There are many types of transducers for many uses. One of them is called the direct current or DC voltage transducer and it’s used for monitoring DC voltages in an electrical system. The DC voltage transducer is not to be confused with the direct-current-powered transducers that get their power from low voltage batteries or similar sources of electricity.

High and Low
A DC voltage transducer is designed for checking low voltages, like those in electrical wiring, and high voltages present in the trip circuits of capacitors. In both cases, they directly measure DC currents, but a shunt may be necessary when measuring voltages much higher than the typical.

DC voltage transducers get their power from either an AC or a DC source. This is why isolation of the DC input and output signals are needed to prevent what is called an earth loop—a current in the ground resulting in potential voltage differences coming from the electrical sources.

Output Signal
The output signal of a DC voltage transducer can be translated for interpretation with an analog/digital meter or by using a number of current management systems. Output is directly proportional to the value of the electrical signal input. Thus, the high-voltage that’s being tested in a system is reflected in the output.

The use of a DC voltage transducer for high-voltage testing is generally for determining if insulation is sufficient for the voltages involved. Low- or medium-voltage testing does not show the weaknesses of insulation since the testing is done below the working voltage level. This is used for less demanding electrical systems.

Above-Normal Helps
The meter of a DC voltage transducer may be calibrated to output for resistance of the insulation to be tested or for the current running through the apparatus. In DC high-voltage tests on insulation, it’s always wise to test above the normal levels expected to determine electrical safety levels.

The practice of over testing covers events like electrical surges, which can be damaging if the insulation is insufficient. The above-normal voltage to be tested can be calculated by multiplying normal peak voltage by a number; the higher the multiplier, the higher the voltage. Just make sure your DC voltage transducer is up to it.