M850 Multi-function Meters



The new range of Hobut multifunction panel meters feature 96 x 96mm sizes complete with unique blue LED screen, which can be seen in direct sunlight. The range is easy to use, features user-programmable CT & VT ratios, and can be used on any single or 3 phase system with any input voltage without re-programming.


The range is a cost effective replacement for traditional panel meters and is suitable for low, medium, and high voltage control panels, gensets, building management systems, power management and more.


Phase Voltage (V)Neutral current measurement.
Phase to Neutral Voltage (V)Reactive Energy(VArh)
Phase Current (I)Power Factor (PF)
Frequency (Hz)Instantaneous Amp Demand
Active Power (W)Instantaneous Watt Demand
Active Energy (kWh)Instantaneous VA Demand
Reactive Power (VAr)Maximum Amp Demand
Apparent Power (VA)Maximum Watt Demand
Maximum VA demand

All models feature the following user-programmable functions.

  • Current Transformer Ratio
  • Voltage Transformer Ratio
  • Baud Rate, parity, stops.
  • AC or DC AUX
  • Single or 3 phase system
  • Input voltage range 28-570V
  • RS485 address, 1-247
  • Security code access for programming.

Both pulsed output (for Wh or VArh) and RS 485 output (Modbus protocol) are plug in options which can be supplied with the multifunction meter. If purchased seperately please use the ordering codes below.

Pulsed Output –
when ordered seperately use PULSE-M850
RS 485 Output –
when ordered seperately use part RS485-M850

Volts/Amps: 0.5% of reading
Frequency: 0.1Hz
Active Power: 1% of reading
Apparent Power: 1% of reading
Power Factor: 2% of range
Energy IEC: 1036 Class 1

Rated Un:28-330V LN,48-570V L-L
Overload: 800V continuous
Burden: 0.5VA per phase
Auxiliary: 100-440V AC / 100-420V DC
Frequency: 45/65Hz

Digits: 3 lines 9999
Size: 14.2mm 7 segment
Brightness: user adjustable

Pulse Output: SPST-NO (10 watt, 300VDC, 500mA)
Pulse Duration: programmable from 40msec-200msec

Test Voltage: 3kv RMS 50 Hz for 1 minute between case, input and aux.
Impulse Test: EMC 5kv transient complies with IEC801/EN55020
Surge withstand: IEC801/EN55020 Ansi C37.90A
Interference: EHF 2.5kV 1Mhz complying to
Protection class II complying to IEC348/BS4753/DIN57411/VDE

General IEC 688, BSEN60688, BS4889, IEC359
EMC: BSEN61000-6-3:2007, BSEN61000-6-4:2007
Safety: IEC 1010, BSEN601010

Working temp 0-60ºC
Storage temp: -40 to +85ºC
Relative humidity: 0-95% non condensing
Shock 30G in 2 planes.

Black polycarbonate case to UL94V0
Weight 0.35Kg

Connection Diagram

Dimensions (mm)

Q. Baud rate setting has changed from my origonal setting

A. The M850 Multifunction meter is intelligent – when you connect it will search for a valid network & automatically set the correct baud rate on its own. If you do not want to do this then you must “LOCK” the baud rate – please refer to section 7 of the Detailed Installation Guide

Q. Voltage is showing on line 3 (when no voltage present)

A. CTs are not earthed correctly. Please refer to section 2 of the Detailed Installation Guide – you must earth the CTs for M850 Multifunction Meter

Q. I do not have any KW reading

A. It is likely that you are trying to measure too little current, ie trying to measure 2A for example with a 150/5 Current Transformer. Ensure your CTs are applicable for the current you are measuring.

Q. When viewing the electrical parameters via RS485, the values are erroneous, some parameters have zero values, and voltage readings are erratic

A. The format of the M850’s Modbus protocol is IEEE754 floating point (32bit or double word) and requires the BMS to be set up the same way. If you set up the Modbus with 2 byte integer (single word) – the values will be incorrect

Q. My energy readings do not seem to be reading correctly – there is a difference of 200 kwh in 24 hours

A. You probably have a current transformer connected the wrong way around. The secondary terminals from the CT must be connected
with S1 terminal on the CT = k on the M850, & S2 terminal on the CT = l on the M850
If a CT is connected backwards, that phase will appear to the M850 as a power source instead of a load.

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