Model 928A Power System Multimeter

Model 928A Power System Multimeter

Handheld, affordable Power System Multimeter measures power and energy, flicker, harmonics, phase angle and includes a waveform display

Model 928A Manual
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Model 928A Data Sheet
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The Model 928A Power System Multimeter with Floating-Point DSP Digital Signal Analysis is an AC Power measurement instrument, providing outstanding performance and flexibility in a small, hand-held package. Not only does the Model 928A measure basic data and power quantities, but it also measures power quality including harmonics, flicker, sags, surges and interruptions. Incorporating a graphic LCD display, serial communications, real time clock and an unprecedented combination of features makes the Model 928A the ideal instrument for the power professional.

For current measurements, Model 928A works with several Arbiter external Current Transformers available as accessories to the unit.

NOTE: The Model 928A Power System Multimeters shipped after 2015 feature a redesigned current input. Read the Press Release for additional information.

Accéder au résumé en français  

  • Downloadable CT characterization files.
  • Low Cost
  • 0.1 % Accuracy
  • Power and Energy
  • Flicker per IEC 61000-4-15
  • Harmonics I, V to 50th, THD
  • Phase Angle I-I, V-V, I-V
  • Waveform Display

Available as a base unit.

Base unit includes:

  • AP0009700 Voltage Probe Lead Set
  • PD0030900 Operation Manual

Also available with Starter Kit.

Starter Kit adds the following to the base unit:

  • AP0009700 Voltage Probe Lead Set (Clarification: two AP0009700's ship when ordering the Starter Kit)
  • AP0011200 External power supply, + 7 Vdc
  • AP0012300 100:1 Clamp-on CT, 150 A, 10 mV/A (1 V @ 100 A ac)
  • AS0082900 928A Bail Assembly
  • BT0000201 Four (4) AA Alkaline cells
  • CA0026106 USB Data Cable, 6 ft
  • CA0027200 CT Cable, Voltage Output
  • CTCAL01 CT characterization, 100 mA to 100 A (other ranges are available for additional fee. Contact sales for more information)
  • HD0069800 928A Soft Carrying Case



Configuration Note

The Arbiter Systems®, Inc. Model 928A Power System Multimeter has two identical measurement channels, Channel A and Channel B. Each input channel has a voltage input and a current input. Current inputs are intended for use with external CTs having a nominal output of 0 Arms to 1 Arms or 0 Vrms to 1 Vrms. For basic measurements (voltage, current, frequency, and phase angle) any combination of inputs may be used. For power and energy measurements (active power, apparent power, reactive power, and power factor), one voltage and one current must be selected.


Input Range

1 Vrms to 660 Vrms


1.2 megohm, differential


Input Range

0.01 Arms to 1.2 Arms or 0.01 Vrms to 1.2 Vrms

Low Range

to < 1 mA or 1 mV


0.01 ohm maximum (current input style) or 100 kohms nominal (voltage input style)


Voltage and Current


Wideband: True rms, 3 kHz Bandwidth
Narrowband: Fundamental magnitude


0.1 % of reading or ± 5 mV, whichever is greater (voltage)
0.1 % of reading + CT errors (current)
1 % of reading + CT errors (low current range)

Phase Angle

A-B Range

0 ° to 360 ° or ± 180 °

A-B Accuracy

0.1 °


< 1 ° typical



50 Hz or 60 Hz ± 5 Hz


0.005 % of reading



Channel A and Channel B, simultaneous


2nd to 50th Harmonic (50 Hz or 60 Hz fundamental)


0.1 % THD + 5 % reading


THD; K-factor; Amplitude bar graph; and individual harmonic magnitude and phase (simultaneous)

Waveform Display

Channel A and/or Channel B



0 MVA or MVAh to 99999 MVA or MVAh
± 99999 MVAR or MVARh
± 99999 MW or MWh
± 1.0000 PF, lead or lag


0.1 % of VA, for VA, VAR, and W
0.001 PF




128 pixel x 64 pixel graphic LCD


30 key keypad




512 KB flash


User setups, Real Time Clock, Approximately 400 KB measurement data

Power Requirements

Internal Battery


4-AA Cells, alkaline or NiMH (not included)


30 hours typical with alkaline cells. 60 hours typical with NiMH



+ 7 Vdc, unregulated (not included)


< 100 mA


5.5 mm x 2.0 mm, center positive




200.0 mm x 104.2 mm x 37.4 mm (7.9 in x 4.1 in x 1.5 in)
381 mm x 305 mm x 229 mm (15 in x 12 in x 9 in), shipping


1 kg (2.2 lbs), net
2.5 kg (5.5 lbs), shipping



Operating: 0 °C to + 50 °C
Nonoperating: - 40 °C to + 75 °C



928AoptCTCHAR CT Characterization
AP0009700 Voltage Probe Lead Set
AS0093800 Operation Manual (928)
AP0001300 1 1000:1 Clamp-on CT, 1000 A (Current Output)
AP0011200 Wall-mount Power Supply: 100-240 Vac, 50-60 Hz; 7 Vdc, 0.714 A
AP0012300 2 100:1 Clamp-on CT, 150 A, 10 mV/A (1 V @ 100 A ac)
AP0012800 1 1000:1, 200 A rms, Clamp-on CT
AP0012900 1 250:5, 500:5, 1000:5, 1000 A rms, Clamp-on CT
AS0071800 Model 928A Starter Kit
AS0079001 Universal Test Plug Current Shunt, A Phase Red
AS0079002 Universal Test Plug Current Shunt, B Phase Yellow
AS0079003 Universal Test Plug Current Shunt, C Phase Blue
AS0082900 928A Bail Assembly
AS0104000 928A CT Cable Compression Ring and Install Tool
BT0000201 4-AA Alkaline cells
CA0026106 USB Data Cable, 6 ft
CA0027100 CT Cable, Current Output
CA0027200 CT Cable, Voltage Output
CN0030500 Adaptor Banana Shielded - Red
CN0030501 Adaptor Banana Shielded - Black
CofC 3 Certificate of Calibration
HD0069800 Soft Carrying Case (928)
MLINK Mlink software

1 Requires CA0027100
2 Requires CA0027200
3 Fee is more when purchased after delivery of 928A.

Click to Download Latest Version of Software
928_Mlink_04Jan2011_0508 Simplifies the modification of various configuration settings
928_UsersCTProg_12Jul2007_010 Allows for CT File Creation and Modification
FTDI_USB_Driver_EXE_2.08.28 Required for USB communications Includes 32 and 64 bit versions in an executable file. The Windows Update Driver Search may also work.
FTDI_USB_Driver_ZIP_2.08.28 Required for USB communications. Includes 32 and 64 bit versions in a zipped file. The Windows Update Driver Search may also work.


Software Version and Related Information


This software interface has been specifically written for the Model 928A.

  • Supports transfer of data from the 928A to your PC.
  • Simplifies configuring complicated measurement functions like Power Quality.
  • Allows upload of latest firmware release to the 928A.
  • Compatible with Windows NT, 2000 and Windows XP
VersionRev LevelVersion Notes
04Jan2011 0.508
  1. Fixed incorrect date when importing/exporting with spreadsheets.
21Jul2010 0.507
  1. Initial release


Utility allows the creation and modification of CT characterization files for Model 928A.

VersionRev LevelVersion Notes
12Jul2007 0.1.0
  1. Initial Release

Utility (FTDI_USB_Driver_EXE)

VersionRev LevelVersion Notes

The latest version. Includes the following versions of the Windows operating system: Windows XP, Windows Server 2003, Windows Vista, Windows Server 2008, Windows 7, Windows 8, Windows Server 2008 R2.

Release Notes

Utility (FTDI_USB_Driver_ZIP)

VersionRev LevelVersion Notes

The latest version. Includes the following versions of the Windows operating system: Windows XP, Windows Server 2003, Windows Vista, Windows Server 2008, Windows 7, Windows 8, Windows Server 2008 R2.

Release Notes

Firmware Information (EPROM based firmware is not available for download)
928_Firmware_11Oct2016_113 Downloadable. Requires 928_MLink version 0.506 or newer.


Firmware Version and Related Information

Downloadable firmware (928_Firmware)

VersionRev LevelVersion Notes
11Oct2016 1.13

Host Version 1.13 11Oct2016

  1. Updated to meet requirements of compiler.

DSP Version 1.05 11Oct2016

  1. Correct the increased phase shift in the 50 Hz due to new current board configuration.

****Use this firmware only if the unit has metal-current input connectors.****

23Feb2011 1.12

Host Version 1.12 23Feb2011

  1. Fix date on firmware version screen.
  2. Minor testing enhancement (BZ638).

DSP Version 1.04 24Feb2010

  1. No Changes.
24Feb2010 1.10

Host Version 1.10 24Feb2010

  1. Limit Flicker values to two decimal digits of resolution (match 933 and 1133).
  2. Fix potential log data download data corruption problem.
  3. Overflow in certain values of Power Quality Config. (BZ 511)
  4. Set default date to 1 Jan 2010, was 6 Jan 2005 (only used when powered for the first time).

DSP Version 1.04 24Feb2010

  1. Harmonic Phase Angles fixed. (BZ 535)
08Jan2007 1.05

Host Version 1.05 08Jan2007

  1. Add factory calibration storage element.
  2. Key repeat feature now limited to only the "Up" and "Down" arrow keys. Also implemented a maximum repeat time (get rid of stuck key keeping the unit powered).
  3. Add units to Thd, RMS-K, Thd-F and Thd-T readings (F1 user screen).
  4. Update to use new "ISR()" macro ("SIGNAL()" macro being deprecated)

DSP Version 1.02 08Jan2007

  1. Updated to support 928 internal CT wiring differences
03Aug2006 1.03
  1. Update menu screens which did not wrap when scrolling through options.
  2. F1 user screen basic data changed to use "normal" non-changing basic data (not effected by hold-min-max-avg).
  3. Fix display of calibration date info (if no calibrations date and Flash modified, it would incorrectly increment to the calibration menu).

Using SensorLink Litewires with the Model 928A
Download Using_SensorLink_Litewires_with_928A.pdf (277 kB) »

Model 928A Current Input Connector Upgrade
Download PD0054400_928a_connector_press_release.pdf (326 kB) »

Model 928A CT Compression Ring Installation
Download PD0054000_928a_comp_ring_install.pdf (646 kB) »

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