BASIC DESCRIPTION AND OPERATION
User’s Manual WM3M4 &WM3M4C
1.1 Description of the device
1.1.1 Functionality of WM3M4 & WM3M4C
The WM3M4 & WM3M4C energy meters are MID certified meters, intended for energy
measurements in the three-phase and single-phase electrical charger stations. The WM3M4C energy
meter features high temperature operation and digital signing for a charging event, whereas WM3M4
features only high temperature operation. Both meters measure energy directly in 4-wire networks
according to the principle of fast sampling of voltage and current signals. A built-in microprocessor
calculates power, energy, current, voltage, power factor, power angle, frequency, harmonics of THD
voltage and THD current harmonics. WM3M4C meter can detect and log events relevant for charging
via RS485 communication. Thus the meter can produce relevant digital signature for charging event.
1.1.2 Appearance
1. RS485 terminals
2. Current terminals – to load
3. LCD display
4. IR COMM PORT – on side
5. QR code (valid only for WM3M4C)
6. DIN-Rail fitting
7. LED indicator (1000 imp/kWh)
8. Current terminal – source (max 40 A)
LCD
Number of digits: 8 (6+2)
Height of digits: 6.52 mm
LED
Colour: red
Pulse rate: 1000 imp/kWh
LED on: no load indication
Figure 1: Appearance of a three-phase electrical energy meter WM3M4C
The energy meters have a built-in optical (IR) communication port on the side as a standard. A special
WM-USB adapter (size 1 DIN module) can easily be attached to it. It can be used for direct
communication with a PC to change settings of devices without any communication installed.
On the housing there are two terminals, A(16) and B(15) for RS485 communication.
Terminals can be sealed with a protective cover to prevent unauthorized access. They are fixed in
accordance with EN 60715.
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