●  Heating
The instrument has a high frequency induction stove for heating which is controlled by the CPU collecting temperature of the
sen sor in the oil cup. The heating process adopt the Switching Power control and PWM control. When the temperature of the sample is too low , the instrument selects the high power heating mode, so it can shorter sample’s heating time. After the temperature gets close to the pre set point the instrument selects low power PWM heating mode for even heating cycle.

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●  Temperature Control
When the real temperature gets close to the setting point, the temperature control CPU select s low power PWM heating mode, and the sample temperature is calculated by PID, and by getting the optimal PWM control duty cycle ,this restricts the temperature to the range of setting temperature error.

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●  Dielectric Loss Measuring
The testing voltage is applied to the internal standard capacitor and voltage terminal simultaneously. After signals of these two lines are PGA controlled by the measuring circuit, the circuit sends the digital signal to DSP (digital signal processor) by using synchronous AD sampling. After the DSP carries out processing of filter, FFT, it figure out parameters of tgδ 、C x 、ε,etc , and send to the main control CPU.

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●  Volume Resistance Measuring
The direct high testing current is applied to the voltage terminal in the oil cup. It produces a faint current signal, the signal is magnified and AD sampled by the measuring circuit ,and is then sen t to the DSP(digital signal processor). DSP processes the signal and figures out parameters of Rx,ρ,etc . Then sends the signal to the main control