MultiDigit Meter

MultiDigit (M842)

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M842 Introduction

The M842 is a compact, three phase power meter. It measures Volts, Amps, Frequency, Active Power, Apparent Power, Reactive Power, Active Energy, Reactive Energy, Power Factor, Amp Demand, Apparent Power Demand, Active Power Demand, Maximum Amp Demand, Maximum Apparent Power Demand, Maximum Active Power Demand, and THD on voltages and currents.
Voltage and current measurements are true RMS.
The MultiDigit is designed to be user friendly and simple to use. All operations, including programming, are performed by using the two push buttons on the front of the instrument. MultiDigit units are pre-programmed by the factory and no further programming is necessary. However, a user can reprogram most parameters in a MultiDigit e.g. nominal current and voltage inputs, relay output etc.

Product code:
M842-SB1 Single Phase
Single Phase 3 wire load
M842-SB4 3 Phase 3 wire unbalanced load
M842-SB9 3 Phase 4 wire unbalanced load


M842 specification

Input (accuracy range)
Rated Un:
Direct connected voltages between 57.8 and 600 V.
Standard voltages offered :-
Three phase four wire- 63.5/110V, 69.3/120V, 120/208V, 220/380V, 230/400V, 240/415V, 277/480V
Three phase three wire- 110V,120V,380V,400V,415V,440V,480V
Range 5-120%
Un Burden 0.5VA per phase

Rated In:
1 or 5A
Range 5-120%
Burden 0.5VA per phase

Frequency 50 / 60 Hz nominal range 45/65Hz

1.5 x Un continuous, 4 x Un for 1 second
4 x In continuous, 50 x In for 1 second

Single phase
Single phase 3 wire
3 phase 3 wire unbalanced load
3 phase 4 wire unbalanced load

Voltage 0.5% of reading ± 2 digitss
Current 0.5% of reading ± 2 digits
Frequency 0.1Hz ± 1 digit
PowerFactor 1% of reading ± 2 digits
Active Power 1% of reading ± 2 digits
Reactive Power 1% of reading ± 2 digits
Apparent power 1% of reading ± 2 digits
Active Energy 1% of reading (IEC 1036)
Reactive Energy 1% of reading (IEC 1036)
Demands 1% of reading ±2 digits

Test Voltage:
3 kV RMS 60 Hz for 1 min between inputs/case/relay output.
2.5kV between RS232 output/inputs/case/relay
Impulse Test:
EMC 5kV transient comply with IEC801/EN55020
HF interference:
EHF 2.5 kV 1 MHz complying with IEC 255-4
Class II complying with IEC348 / BS4753 / DIN 57411 / VDE 0411

Working Temperature -20 to +70 °C
Storage Temperature -40 to +85 °C
Temperature Coefficient 0.01% per °C
Relatively Humidity 0-95% non condensing
Warm up time 1 min.
Shock 30g in 3 planes

Standard ANSI 4.5"
Mounting Terminals Via 4 1/4"-28 screws
Panel Cutout 4.0" Diameter
Material Polycarbonate complying with UL 94 VO
IP Rating NEMA 4 / IP54
Weight 1.6lb

Applied Standards
General IEC 688 BSEN60688, BS4889, IEC 359
EMC Emissions EN61326-1
Immunity EN61326-2
Safety EN61010-1

Pulsed output W.h or VAr.h, user programable
Relay - N/O volt free contact 50V 150mA 5W ac/dc
1 pulse per W.h or kW.h or MW.h depending on input values. Pulse duration programmable in steps of 20ms from 20ms to 200 ms.

RS 232 or RS 485
Baud rate programmable 19200, 9600, 4800, 2400
Parity programmable Odd, even or none
Stop bits programmable 1 or 2
Addresses programmable 1 to 247 (RS485 only)
Transmission distance 15 metres RS 232
Transmission distance 1.2kM RS 485

Measurements Displayed
Volts L1-L2,L2-L3,L1-L3 (3 ph 3 & 4 wire) L1-N,L2-N,L3-N (1 ph & 3ph 4wire)
System frequency
System power factor
System active power
System reactive power
System active energy
System reactive energy
System apparent power
System demands (Current, Watts and VA)
System peak demand (Current, Watts and VA)
THD voltages and currents