Switching Mode Power Supply is adopted to almost Household Appliances and Office Automation Equipment
The inputted current waveform is distorted like pulse wave and also voltage waveform is distorted same point as current. It includes so much harmonic components because of circuit design of capacitor input style.

Requirements for Power Meter;

Type of Inverter : PWM is main method and PAM becomes popular

PWM(Pulse Width Modulation) : Revolution speed of motor is controlled by using change of pulse width of voltage waveform. And there are two types of method in PWM. One is Sinusoidal PWM and another is Square-wave PWM. The Sinusoidal or Square- mean current waveform of motor input.

PAM(Pulse Amplitude Modulation) : Revolution speed is controlled by amplitude of voltage. And the waveform both voltage and current are square. Therefore, frequency bandwidth of measuring instrument for current is required higher than PWM type inverter.

Requirements for Power Meter;

Inverter for high frequency fluorescent lamp
In general, the waveform is a kind of triangle or sinusoidal. And the fundamental frequency is below 100kHz. Also envelope is twice of commercial frequency.

Requirements for Power Meter;

Measuring method of fluctuating Electric Power (for example : Copying machine)

Requirement of Power Meter ;