Main Features:
1. Energy Measurement Function: Measure forward/ reversal, active/ reactive energy
2. Instantaneous Parameters Measurement Function: measure instant active/reactive
    total power. phase voltage/ current/ power factor, frequency
2. Pre-payment function, and prepayment is loaded through 20-digit token
3. Tariffs function: support TOU tariffs and step tariff
4. Load control function Load limit configurable.
5. Events detection and record function, include cover opening, reverse, overload etc
6. Remote switch control functions: remote switch disconnect/ reconnect.
7. Message alarm function: the meter will inform users By sending message if
    disconnect when energyReaches zero or power overload etc.
8. Communication function: with RS485 communication Port and infrared Port.
9. RTC:  clock with calendar, timing,leap year Automatic conversion function.
10. Alarm by LED/Buzzer when low credit , overload, tamper.
11. Relay control: (1) the internal relay will be switched off when the top cover is
     opened (2) overload (3) out of remaining balance (4) RTC battery power down