Model 931A Power System Analyzer

Full featured Model 931A goes beyond basic and power quantity measurements, supporting two way communications, transducer calibration, timer features and more.

Model 931A Manual
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Model 931A Data Sheet
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Model 931A, with state-of-the-art PowerDSA^™ Digital Signal Analysis, make more measurements, more accurately, and at a lower price than ever before. Basic accuracy of 0.05 % of reading and 0.05 ° phase, harmonic analysis, and full three-phase capability are standard. Model 931A also incorporate full two way serial communication for use in power quality trend monitoring. The model expands usability by including transducer calibration and timer features.

Model 931A, featuring PowerDSA^™ Digital Signal Analysis, measures all of the basic quantities: true-rms voltage and current, frequency and phase angle, as well as power quantities such as watts (W), watthours (Wh), volt-amperes (VA), volt-ampere hours (VAh), volt-amperes reactive (VAR), volt-amperes reactive hours (VARh), and power factor (PF), all with 0.11 % basic accuracy.

Measure harmonics and view the results graphically on the high contrast 240x64 graphic display. The two channels are normalized to Channel 1 fundamental phase, so you can see, for example, the relationship between current waveform distortions and voltage phase.

Other key functions include a timer/counter for measuring relay operating times, elapsed test times, or for counting input rates and events. The 931A include a full three-phase input section, for automated three-phase measurement sequences, complete with multiple display modes (see Key Features tab, below)

Key Features
Specs
Options
Accessories
Software
Firmware
Related Resources

Top-of-the-line Power Measurement and Analysis product
Measures basic and power quantities
High accuracy
Field ready
Multiple display options including three phase displays

Basic three-phase display - Voltage, current, phase, frequency and power quantities on one convenient display.
Vector display - view voltages, currents and phase angles with their vector representation.
Voltage/Current Sequence display - view voltage, current and phase along with positive, negative and zero sequence values.
Energy display - view voltage, current, phase, frequency and energy quantities on one convenient display.

Power Trend Monitor and recording system - verify phase relation, phase rotation, power direction, load balance and more
Transducer Calibration supported
CT/PT Ratios
Extended Measurement Ranges

Input

Basic Inputs	Supports two main measurement channels, Channel 1 and Channel 2. Any voltage or current input signal may be selected for either channel. For basic measurements (voltage, current, frequency, 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. For three-phase measurements, the input configuration is selected automatically, based on the measurement type (for example, 3-phase 4-wire 3-element).

Voltage

Input Range	1.5 Vrms to 750 Vrms (underrange to 200 mV) [2 Vdc to 1000 Vdc (Model 931A Only)]
Inputs	Four; A, B, C, N Phase-to-Phase Phase-to-Neutral Phase-to-Synthesized Neutral (A+B+C / 3)
Impedance	1 megohm
Leakage	< 3.5 mA per IEC348 and UL1244

Current

Input Range	0.04 Arms to 20 Arms (underrange to < 1 mA)
Inputs	Three; A, B, C, plus synthesized neutral
Burden	0.01 ohm maximum
Isolation	Transformer, 1000 Vrms
Neutral	Synthesized, -(A+B+C)

Timer

Inputs	Two; 4 Vdc to 300 Vdc; 20 Vrms to 300 Vrms; or dry contact/thyristor output
Isolation	Optical, 300 Vrms, each channel

Transducer

Range	0 to 1, 0 mAdc to 100 mAdc and 0 Vdc to 10 Vdc
Protection	Overvoltage to 120 V, both inputs
Isolation	Optical, 300 Vrms

Measurements

Voltage and Current

Method	Wideband: True rms, 3 kHz Bandwidth Narrowband: Fundamental magnitude
Accuracy	0.05 % of reading
Underrange	< 1 % of reading, typical at 0.3 mArms
DC Voltage	0.1 % of reading + 25 mVdc, typical

Phase Angle

Input	Channel 1 to Channel 2
A-B Range	0 ° to 360 ° or ± 180 °
A-B Accuracy	0.05 °
Underrange	< 1 °, typical at 0.3 mArms

Frequency

Input	Channel 1
Range	20 Hz to 500 Hz (underrange to 5 Hz)
Accuracy	0.005 % of reading

Harmonics

Input	Channel 1 or Channel 2
Range	2nd to 50th Harmonic (50 Hz or 60 Hz fundamental)
Accuracy	0.01 % THD + 5 % of reading
Display	THD; K-factor; Amplitude bar graph; and individual harmonic magnitude and phase (simultaneous)

Waveform Display

Channel 1 and/or Channel 2

Power

Range	0 MVA or MVAh to 99999 MVA or MVAh ± 99999 MVAR or MVARh ± 99999 MW or MWh ± 1.0000 PF, lead or lag
Accuracy	0.11 % of VA, for VA, VAR, and W 0.001 PF

Timer

Range	0.0001 seconds to 9999.9 seconds, or 0.01 cycles to 999999 cycles
Accuracy	0.005 % of reading + 1 digit
AC Trigger	Add 1 ms maximum, 0.15 ms at 120 Vrms

Transducer Accuracy

0.05 % of reading + 0.01 % range

Interface

Operator

Display	240x64 graphic LCD with cold-cathode fluorescent lamp (CCFL) backlight
Keypad	21 function keys plus On/Off
Memory	EEPROM (calibration data) Battery backup RAM (setup and stored results) Real-time clock
Data	Instrument calibration data User setups (up to six) Logged data (15 to 200); time-tagged

Power Requirements

Internal Battery

Type	Nickel-Metal Hydride (NiMH)
Operation	8 hours typical
Charging Time	8 hours typical; fast + float charge

External

Range	85 Vac to 264 Vac, 47 Hz to 440 Hz, 15 VA maximum 110 Vdc to 250 Vdc, 15 W maximum
Safety	Designed to meet UL, CSA, VDE

General

Physical

Instrument/Size	205 mm x 305 mm x 225 mm (8 in x 12 in x 8.75 in) 483 mm x 483 mm x 483 mm (16 in x 16 in x 16 in), shipping
Weight	5.8 kg (12.8 lbs), net 8.2 kg (18 lbs), shipping

Environmental

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

There are no additional Options available for this product.

Included
812	Safety Ground Lead
AS0094000	Operation Manual (931A)
CA0019806	RS-232 Null Modem Cable, DB9F-DB9F, 2 m (6 ft) length
P09R	Power Cord, North America, Right Angle
Available
09311A	400 A 20:1 Precision CT, 0.1 % Accuracy
811AT-8	3-Phase Univ. Test Plug Current Lead Set
813AT-8	3-Phase Safety Voltage Lead Set
815AT-8	Model 815 Fused Safety Voltage Probe Lead Set
816AT-8	3-Phase Spade-Lug Current Lead Set
817AA-8	1-Phase Clamp-On CT Test Lead
817AT-8	3-Phase Clamp-On CT Lead Set
818AT-8	3-Phase Safety C-Hook Current Lead Set
819xyz-8	Modified Safety Clip Lead Set
841A	Series Test Jack Isolator Paddle
842A	Three - Series Test Jack Isolator Paddles with 60 cm Nylon Cord
842B	Four - Series Test Jack Isolator Paddles with 60 cm Nylon Cord
AP0001300	1000:1 Clamp-on CT, 1000 A (Current Output)
AP0012800	1000:1 Clamp-on CT, 200 A, 1 mA/A (100 mA @ 100 A ac)
AS0035901	Adjustable Tilt Handle/Bail Assembly
AS0036000	400 A CT Bracket (each)
AS0060000 ¹	PowerCSV Application Software for Models 931A and 930A
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
AS0079030	Universal Test Plug Current Shunt, Set of Three
CN0030500	Adaptor Banana Shielded - Red
CN0030501	Adaptor Banana Shielded - Black
P01R-P10R	Country specific power cord with right angle female end

¹ Available via download only

Click to Download Latest Version of Software
930/31_PowerCSV_14Oct2010_2002	For Models 930 and 931 - requires memory option
930/31_PowerCSV_SHA256_14Oct2010_2002	930/31_PowerCSV SHA256 checksum
Tera Term_01Jan2010_23	Terminal program that can capture data from Models 930A and 931A. Also, can program the Satellite Clocks via serial commands. Modern version is available from their website: https://teratermproject.github.io/index-en.html
Tera Term SHA256_01Jan2010_23	Tera Term SHA256 checksum

Software Version and Related Information

Common Controls Update for PowerCSV

04Oct2002

Current

PowerCSV for Models 930 and 931 (930/31_PowerCSV)

Version	Rev Level	Version Notes
14Oct2010	2.002	Fixes downloading of Standard Data Log issue Increments version to 2.002 Updates copyright 2010 Uses new Installer to ensure consistency across Arbiter product installers
28Apr2009	2.001	Current release

930/31_PowerCSV_SHA256

Version	Rev Level	Version Notes
14Oct2010	2.002

Terminal Emulation Program (Tera Term)

Free software terminal emulator (communications program) for Microsoft Windows.

Tera Term (Pro) is a free software terminal emulator (communication program) for MS-Windows.
Supports VT100 emulation, telnet connection, serial port connection, etc.

Tera Term SHA256

Firmware Information (EPROM based firmware is not available for download)
929/30/31_Firmware_05Dec2018	Requires an EPROM update from Arbiter. The same update works for Models 929, 930 and 931.

Firmware Version and Related Information

EPROM update (929/30/31_Firmware)

Version	Rev Level	Version Notes
05Dec2018		Updates are not security related. Fixed word wrap on display when prompted to set defaults (BZ 841).
13Jul2018		Updates are not security related. Added check of battery backed RAM data. If corrupted then prompts to set defaults. Set default backlight control to AUTO. Added support for NiMH battery.
08Dec2010		Fixed: CT/PT scale factors were enabled upon setting factory defaults. (Reference BZ642)
10Feb2010		Problems erasing single log file. (BZ 599) Update RS232 output to replace Null (0x00) bytes with space (0x20)

App Note 110: Measuring Low-Level Signals w/Model 931A
Download application_note_110.pdf (25 kB) »

App Note 113: Using Clamp-On Current Transfomers (CTs) with Arbiter Power Analyzers
Download application_note_113.pdf (89 kB) »

Logging Files from the Model 931A Power System Analyzer
Download pd0044600_logging_931_930_data_with_teraterm.pdf (142 kB) »

Model 09311A 400 Amp Auxiliary Current Transformer
Download 09311a.pdf (252 kB) »

Model 09311A 400 Amp Auxiliary Current Transformer Español
Download 09311a_ct_espanol.pdf (125 kB) »

Overview Presentation of Model 931A Power System Analyzer
Download 931a_seminar.pdf (732 kB) »

Sealed Nickel-Metal Hydride cells (MSDS)
Download sealed_nickel-metal_hydride.pdf (558 kB) »