**9.2 Test on the commercial programmable signal generator**

The commercial programmable signal generator not only provides sinusoidal fundamental waveform voltage and current signals, but also enables the modification of these waveforms to include harmonic components for the calibrations of harmonic meters. It is specified as a 0.02% device (a standard source).

The performance of the programmable signal generator is also verified using the harmonic power standard equipment. The generator is programmed to produce the set of IEC signals of fundamental 50 Hz 100 V, 3 A, and cos = 1, and 5th harmonic 10 V, 1.2 A, and cos = 1. The measured results are compared with the set values of the signal generator. The fiducial harmonic errors of voltage, current, and power from the DC to the 7th order harmonics are shown in Table 9.2.1 They basically confirm the specifications of the signal generator.

However, a small non-linearity effect in the current output is observed. Larger errors are generated at the DC, 2nd, 4th, and 6th order harmonic currents. This result may be indicative of a non-linearity effect. Given the square of the fundamental component that produces the DC and 2nd order harmonic components, the cross term of the fundamental and 5th order harmonic component produces the 4th and 6th harmonic components. A similar but less noticeable phenomenon can also be observed in the voltage output. The occurrence of the non-linearity effect should be confirmed through other tests.


Table 9.2.1. Fiducial harmonic errors of the signal generator at the IEC signal
