1-4
IM 253710-01E
Motor module Model: 253771
The signal applied to the revolution sensor signal input connector (CH7) and the
torque meter signal input connector (CH8) of the motor module is normalized using
the voltage divider and the operational amplifier (OP AMP). The voltage is then input
to the A/D converter and the zero crossing detector.
• When the signal from the revolution sensor and torque meter is a DC voltage
(analog input)
The A/D converter samples the voltage/current input signals using the sampling
clock provided by the internal circuit of the 253710, converting the signals to digital
data. The sampling rate is fixed to 5 MS/s for the normal measurement mode, and
integer multiples of the PLL source for the harmonic measurement mode (approx.
80 k to 160 kS/s). The sampling operation can also be carried out using a clock
signal that is applied to the external clock input connector.
• When the signal from the revolution sensor is a pulse signal
A count value is output in place of digital data of the A/D converter. The counter
counts the signal that is output by the zero crossing detector from the rising edge to
the falling edge (one period) using the reference clock (internal clock) and updates
the count value.
PZ4000 main unit Model : 253710
The output from the A/D converter and the zero crossing detector of the module is
passed to the main unit of the 253751 via the photo isolator. Up to eight channels of
sampled data and zero crossing data are recorded into the acquisition memory (ACQ
memory) along with the external trigger and external clock conditions according to the
sampling rate that is automatically determined by the specified observation time (see
page 1-15).
The digital signal processor (DSP) determines the voltage, current, and active power
(also reactive power for harmonic measurement mode) from the sampled data in the
acquisition memory. The display ASIC processes the numerical and waveform data
so that they can be displayed.
In order to accurately determine the basic measurement items for currents (voltage,
current, active power (also reactive power for harmonic measurement mode)), the
sampled data must be averaged over a period in sync with the period of the input
signal. To do so, the DSP uses the zero crossing data and external clock and
external trigger conditions.
In addition, the DSP calculates additional items from the basic measurement items.
Among these additional items are the apparent power, the reactive power (for normal
measurement mode), the power factor, phase difference, impedance, and
Σ
.
1.1 System Configuration and Block Diagram
