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1.2.17 Power supply consumption …………….…. 2.8 V
⋅
А;
Input power consumption:
- current circuit …………………….…… 0.2 V·A;
- voltage circuit (U nom = 100 V) …........ 0.2 V·A;
- voltage circuit (U nom = 380 V) …..….. 0.6 V·A;
1.2.18 Overall dimension ….. 120x80x120 mm.
1.2.19 Weight ………………. 0.85 kg.
1.3 Construction
1.3.1 General Form of the transducer is presented in Annex A.
1.3.2 Transducer has the following parts:
-
Interface board;
-
Meter board;
-
Case;
-
Cover.
Interface board and Meter board are produced of fiber-glass plastic with surface-mount technology.
Case and Cover are produced of plastic material.
Interface board and Meter board connect through leading-in sockets.
Supply transformer and three measuring transformers are on the meter board. Inside a case the meter
board is arrested by guide ridge.
The contacts established on a cover ensure strengthening of the interface board.
The cover is mounted to a case through four screws, which can be sealed up.
The connection on the RS-485 service interface is made through a special hole in a cover. The hole is
closed by a protective patch.
The latch ensures mounting the transducer to the rail or panel depending on variant of installation.
1.4 Functional description
1.4.1 The transducer is a device with digital processing of a signal.
The transducer consists of following reference nodes:
– Metering Circuit;
– Interface;
– Power source.
1.4.2 Metering Circuit consists of three identical measuring lines.
Each measuring line contains a voltage channel and current channel.
Each channel consists of input stage, low-pass filter (LPF), analog-to-digital converter (ADC) and
computational part.
When reactive power is measured, a Hilbert transformer is used in the computational part of the vol-
tage channel.
Voltage cascades are the scaling amplifiers and have immediate galvanic communication with input
voltage circuits. Current cascades are carried out with the compensation circuits on measuring transfor-
mers and ensure a galvanic isolation of the measuring current circuits.
The input cascades convert input signals of voltage and current into the proportional output voltage
that is transmitted to inputs of six-channel ADC.
ADC functions the discrete sampling and converting of the input signal into a 16-bit binary code.
Sampling frequency is 3125 Hz.
Calculation of parameters which the transducer output delivers is realized by microcontroller.
1.4.3 Basic formulas are presented in tables 8, 9.
