Product Manual WS74
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Copyright
DZG Metering GmbH, Heidelberger Str. 32, D-16515 Oranienburg
Copies only are allowed authorized by DZG
2/22/2019
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11
Block diagram
11.1
The whole block diagram
The block diagram for whole system is as follow:
Figure 9 Block diagram
The whole platform is with the RC-power supply, current sampling by shunt, voltage sampling by
resistor divider, data storage by EEPROM, display by segment LCD and SOC of HT5015.
Meter provides the bi-direction communication by optical port for user interface, calibration interface
for manufacture production.
By external tariff switching terminal, meter can record the 2-tariff energy. Magnetic field detection
circuit detects an external magnetic field.
There is power off detection circuit. It is used to monitor the voltage status.
With push button or optical button input, the display information can be switched.
11.2
Measurement part
The meter is able to measure active energy in accuracy class 1 (Class B) using measurement unit
embedded in the SOC.
The basic operation is that the device multiplies the instantaneous voltage and current together to give
the instantaneous power consumption at the high precision. It then integrates these power units a pre-
set quantity has been used, the consumption of this small packet of power is very small. The
measurement value of the active power is indicated by the LED (the period is based on current
loading).
The voltage is sensed at the inputs to the meter and passed via a high voltage resistor chain to the
component. The resistor chain is used to limit the sampling voltage added into the measurement
component. This value will not bigger than 400mVP-P.In this voltage chain there are some capacitors.
It is also important that though these the high frequency signals in the voltage input circuit are filtered
on the inputs, and then the measurement unit can sample the input channel without high frequency
interface.
