Arbiter Systems 918B User manual

Model 918B
Phase Angle Multimeter
Operation Manual
Arbiter Systems, Inc.
Paso Robles, California
U.S.A.
Printed in U.S.A.

ii
This manual is issued for reference only at the convenience of
Arbiter Systems. Arbiter Systems has made reasonable effort
to verify that all diagrams, to the best of our knowledge, are
accurate as of September 5, 2001. However, due to
production changes and availability of parts, these diagrams
are subject to revisions and modifications. Check with Arbiter
Systems at the address below for any revisions made since
this publish date. Arbiter Systems, Inc.
1324 Vendels Circle
Suite 121
Paso Robles, CA 93446
[phone]
www.arbiter.com
[email protected]

iii
Model 918B
PHASE ANGLE MULTIMETER
Operation Manual
Arbiter Systems, Inc. 2001.
All rights reserved. International copyright secured.
PD0010600C

v
Table of Contents
Table of Contents.................................................................v
1.0 Introduction.....................................................................1
1.1 Features........................................................................................1
1.2 Accessories Included...................................................................3
1.3 Accessories Available..................................................................3
1.4 International Power......................................................................3
1.5 Safety Precautions .......................................................................4
1.6 Factory Service............................................................................5
Extended Warranty............................................................................6
2.0 Operation.........................................................................9
2.1 Instrument Power.........................................................................9
2.1.1 Operation from the AC Line.....................................................9
2.1.2 Operation from the Internal Battery .......................................10
2.1.3 Battery Test.............................................................................10
2.1.4 Charging the Internal Battery .................................................10
2.1.5 Auto Power-Off......................................................................11
2.2 Power On...................................................................................11
2.2.1 Initial Configuration ...............................................................11
2.3 Measurement of DC Volts.........................................................18
2.4 Measurement of AC Volts.........................................................19
2.5 Measurement of AC Amperes...................................................20
2.6 Measurement of Volt Amps (Apparent Power).........................22
2.7 Measurement of Volt Amps Reactive (Reactive Power)...........24
2.8 Measurement of Watts (Active Power) .....................................27
2.9 Measurement of Power Factor...................................................30
2.10 Measurement of Frequency .....................................................32

vi Table of Contents
2.11 Measurement of Phase Angle.................................................. 34
3.0 Special Functions and Features..................................37
3.1 Automatic and Manual Range Selection................................... 37
3.1.1 Description of Ranges............................................................ 37
3.1.2 Automatic Range Selection.................................................... 39
3.1.3 Manual Range Selection......................................................... 39
3.2 Minimum and Maximum Value Storage................................... 41
3.3 Using Delta Phase for Phase Comparison Measurements ........ 42
3.3.1 Using Fixed Offsets in Delta Phase Mode............................. 43
3.4 Watt-Hour Measurement........................................................... 44
3.5 Making Voltage-to-Voltage Phase Angle Measurements......... 45
4.0 Specifications ...............................................................47
4.1 Measured Parameters: ............................................................... 47
Voltage (RMS and DC):.................................................................. 47
Phase................................................................................................ 48
Frequency........................................................................................ 48
4.2 Calculated Parameters............................................................... 49
4.3 General Specifications............................................................... 50
Warranty..............................................................................53
List of Figures
Figure 1 – 918B Front Panel............................................................. 7
Figure 2 – Phase Convention, Lead 0 - 360º................................... 16
Figure 3 – Current Transformer Orientation................................... 26

1
1.0 Introduction
This manual provides operating instructions and specifications for
the Arbiter Systems Model 918B Phase Angle Multimeter.
1.1 Features
The Model 918B Phase Angle Multimeter is a compact,
microprocessor-controlled instrument capable of ten functions,
which have been optimized for use in applications involving AC
power transmission and distribution.
The following parameters are measured directly by the 918B:
DC Volts: 0.2 V to 1 kV
AC rms Volts: 0.2 V to 1 kV
AC rms Amperes: 0.02 A to 20 A (0.002 A to 1000 A*)
Frequency: 45 Hz to 500 Hz
Phase Angle: 0 to 360 degrees
The following parameters are calculated, based on measured values:
Watts: Vrms×Irms×cos Θ0.004 W to 20 kW
(1000 kW*)
Volt-Amps: Vrms×Irms 0.004 VA to 20 kVA
(1000 kVA*)
VA Reactive: Vrms×Irms×cos (-Θ) 0.004 VAR to 20 kVAR
(1000kVAR*)
Power Factor: cos Θ-1.0 to +1.0, lead or lag
Watt-Hours 0 to 9999 kWH
*With optional accessories.

2 Introduction
The 918B accepts inputs via two pairs of front panel jacks; one pair
for voltage, and one pair for current (optional adapters allow
voltage-to-voltage phase measurements). The voltage connections
are made directly to the circuit under test, using leads included with
the instrument. The current input is voltage-isolated from the circuit
under test by means of a clamp-on current probe (also included),
which offers the added advantage of allowing measurement of
current without opening the circuit.
A 16-character supertwist liquid crystal display provides a clear
indication of the parameter being tested, and the value measured.
Selection of functions and ranges is accomplished via a user-friendly
front panel interface, consisting of eight pushbuttons. Auto-ranging
simplifies operation by minimizing user keystrokes, or the ranges
can be set manually.
A "Hold" function allows the user to "freeze" the values for all
parameters at the press of a button. A "Minimum/Maximum"
function permits recording of the individual minimum and
maximum values that occur for each function, within a time frame
that is controlled by the user.
A unique feature of the 918B is the "Delta Phase" mode, which
allows measurement of the phase angle between two voltages (or
currents), using any synchronous current (or voltage) as a reference.
This allows, for example, comparison of all of the phase angles in a
three-phase system, without requiring simultaneous connection to all
of the phases.
The ability to operate from either the internal nickel-cadmium
rechargeable battery, or from the ac line (with supplied plug-in
transformer) makes the unit suitable for both hand-held and
benchtop applications.

Introduction 3
1.2 Accessories Included
The following accessories are included with the 918B Phase Angle
Multimeter:
•Test probe kit, with screw-on adapters; part no. AP0002000A
•Battery charger, 120 vac/60 Hz; part no. AP0001100A (see
"International Power" below for other line voltages and
frequencies)
•1000:1 Clamp-on Current transformer, part no. 09111A
•Current transformer cable, part no. CA0014300A
•918B bail, part no. HD0033800A
•Soft carrying case, part no. HD0033600A
•Operation manual, part no. PD0010600B
1.3 Accessories Available
The following accessories are available from Arbiter Systems, for
use with the 918B Phase Angle Multimeter:
•Maintenance and Calibration Manual, part no. PD0011100A
•Auxiliary voltage adapter, 10-750 V (for direct voltage-to-
voltage phase angle measurements), Model 09184A
•Plug-in CT/adapter, 0.002-2.0 A direct input, Model 09182A.
•Plug-in CT/adapter, 0.02 - 20 A direct input, Model 09182B.
•1000 Amp Clamp-on Current Transformer, Model 09113A
(must be used with Model 09182A)
1.4 International Power
Battery chargers for international operation are currently available.
Contact Arbiter Systems for more information about these chargers.
If operation on a different line voltage becomes necessary, any
power supply capable of generating 15 volts dc at 150 mA minimum
may be used for charging. A 3.5mm (1/8") miniature phone plug, tip

4 Introduction
positive and sleeve negative, will allow such a power supply to be
used to operate and charge the 918B.
1.5 Safety Precautions
The following general safety precautions must be observed during
all phases of operation of this instrument. Failure to comply with
these precautions or with specific warnings elsewhere in this manual
violates safety standards for the design and intended use of the
instrument. Arbiter Systems, Inc. assumes no liability for the user's
failure to comply with these requirements.
Beware of Hazardous Voltages
The 918B Phase Angle Multimeter is capable of measuring voltages
up to 1000 volts. Use extreme caution when working around high
voltages. Failure to do so could result in personal injury or death.
Do Not Connect (-) Input Terminal to Voltages in Excess of ±
±±
±25
Volts From Earth Ground.
The 918B was designed for use with the (-) input connected to
ground or circuit neutral. Application of more than ±25 volts with
respect to earth ground may result in the potential for electric shock
or damage to the instrument. This precaution is of particular
importance when the charger is connected to the instrument.
Do Not Make Current Connections Directly to the 918B Current
Input.
The current inputs of the Model 918B are designed to accept only
the output of a current transformer. The transformer is necessary to
provide voltage isolation, and to convert the measured current to a
value that can be safely applied to the current inputs of the
instrument. Never connect the current to be measured directly to the

Introduction 5
current input; damage to the instrument and/or hazardous conditions
may result. Always use the supplied current transformer or one of
the other current transformers or adapters available from the factory
(see "Accessories Available", section 1.3).
Replace Fuses with the Proper Size and Type.
A pair of ¼ amp, 250 volt, 2AG type fast-blow fuses protect the
current inputs of the 918B (Arbiter Systems part number
FU0001603A). Replace only with fuses of the same type and rating.
Do Not Substitute Parts or Modify Instrument
Because of the danger of introducing additional hazards, do not
install substitute parts or perform any unauthorized modification to
the instrument. Return the instrument to Arbiter Systems for service
and repair to ensure that the safety features are maintained.
The preceding safety precautions may appear in other sections of
this manual, where appropriate for the specific operations being
described.
1.6 Factory Service
Should the instrument need to be returned for factory service, please
contact the Arbiter Systems Service Department to obtain a Return
Material Authorization (RMA) number. You must provide the serial
number of the instrument in order to obtain an RMA number. If your
instrument is covered by warranty, see our "Limited Warranty"
description at the end of this manual. If your instrument is not
covered by warranty, we will provide a copy of our current service
policy and price list. If return of an instrument is authorized, forward
the instrument prepaid to Arbiter Systems.

6 Introduction
Extended Warranty
Arbiter Systems also offers an extended warranty available in one
year increments. You may purchase the extended warranty at any
time before your standard one year warranty expires. Please contact
our sales department for more information about our extended
warranty.

Introduction 7
+—
—
+
1000 Vrms MAX
1000 Vdc MAX 45 - 500 Hz CT OUTPUT ONLY 25 mArms MAX
25V
MAX
POWER
AT POWER ON
USE "HOLD" KEY TO CHANGE CT RATIO
USE "PHASE" KEY TO CHANGE PHASE MODE
Vdc VA VAR RANGE
Vrms Arms W/Whr HOLD
SHIFT
PHASE PF START
PHASE FREQ MIN/MAX
∆
CURRENT TRANSFORMER TERMINALS ARE AT SAME
POTENTIAL AS (–) VOLTAGE INPUT.
USE PROPER PRECAUTIONS.
FUSED
Figure 1 – 918B Front Panel

9
2.0 Operation
This section provides detailed instructions for the individual
operating modes and features of the 918B Phase Angle Multimeter.
Figure 1 provides a reference for front panel controls and input
jacks. Also, abbreviated descriptions of the main features are printed
on the rear panel of the instrument, for quick reference.
Be certain to observe safety precautions, where noted.
2.1 Instrument Power
2.1.1 Operation from the AC Line
The 918B Phase Angle Multimeter may be operated for an indefinite
period of time from the ac line, using the included external power
supply. All measurement functions can be performed while the
instrument is connected in this manner. To operate the 918B from
the ac line, connect the 3.5mm (1/8") mini plug into the power jack
on the rear panel, and plug the power supply into an ac line socket.
Caution Do not exceed ±25 volts peak, with respect to earth ground
on the (-) voltage input. The 918B is designed to operate with the (-)
input connected to earth ground or circuit neutral.
NOTE Characters will always be present on the display when the
power pack is connected and plugged into the ac line. When the unit
is turned on, the displays associated with normal operation will be
present. After the "Power" key is pressed to turn the unit off, or after
auto power-off occurs (see section 2.1.5), the display will indicate
the battery charging status.

10 Operation
2.1.2 Operation from the Internal Battery
The 918B Phase Angle Multimeter features an internal 9.6 volt
nickel-cadmium rechargeable battery, which will permit operation
of the instrument for a minimum of 25 hours between charges.
2.1.3 Battery Test
At initial power-up the instrument will automatically perform a
battery voltage measurement. If the battery voltage is above 11
volts, the instrument will recheck the voltage once per hour. When
the measured voltage falls below 11 volts, the frequency of the
battery voltage test will increase to once every fifteen minutes.
When the battery voltage falls below approximately 9.2 volts, the
display will indicate "LoBat". At this point, the charger should be
connected.
Whenever the momentary battery test is being performed, the
display will change briefly to read, "Battery Test".
2.1.4 Charging the Internal Battery
To charge the 918B internal batteries, connect the power pack to the
ac line and the power inlet jack on the rear panel. Internal power
management circuitry will automatically evaluate the charge state of
the battery, and select one of two charging rates. A high charging
rate is applied initially, until the battery is near full capacity. After
this, a lower, "trickle" charge rate is used, allowing the 918B to be
connected to the ac line indefinitely without danger of overcharging.
When the unit is turned off during charging, the front panel display
will indicate which of the charge rates is being used, and the voltage
of the battery. This display is updated every 15 minutes.
A completely discharged battery will require approximately 6-8
hours to reach full charge. To maximize the operational life of the
battery, it is advisable to allow full discharge prior to recharging.

Operation 11
2.1.5 Auto Power-Off
To increase battery life, the 918B includes an automatic power-off
circuit. In order for the unit to turn itself off, all of the following
conditions must be met continuously for a period of 20 minutes:
•No keystrokes;
•Voltage level of less than 1 volt at the voltage input;
•Current level of less than 20 milliamperes at the current input.
After auto power-off has occurred, normal operation may be
resumed by pressing the "Power" key.
If the power pack is connected when auto power-off occurs, the unit
will switch to the battery charge mode, and give a continuous
display of charging status (see section 2.1.4, "Charging the Internal
Battery"). When the instrument is turned back on, it will return to
the same set of operating conditions that were present when auto
power-off occurred, provided the power pack remained connected
the entire time that the unit was off.
2.2 Power On
To begin operation of the 918B, first verify that any voltage and/or
current connections to the inputs are in compliance with the limits
shown on the front panel. Press the front panel button labeled
"POWER". The display will provide a momentary indication of the
selected current transformer, then a momentary indication of the
selected phase convention.
2.2.1 Initial Configuration
The default values for some of the 918B configuration settings may
be modified to accommodate special test circumstances or external
equipment options. These changes can be made at initial power-up,
using the following instructions.

12 Operation
2.2.1.1 Changing the CT Configuration
The current input of the Model 918B Phase Angle Multimeter is
designed for operation with a current transformer, which reduces the
measured current to a level that can be accommodated by the
instrument. The standard clamp-on current transformer included
with the 918B has a ratio of 1000:1. The step-down ratio of other
current transformers to be used in conjunction with the 918B is
dependent on the range of currents to be measured. The 918B
accepts 20 milliamperes maximum.
NOTE The Model 918B Phase Angle Multimeter incorporates
special circuitry to compensate for impedance characteristics of
Arbiter Systems' current transformers. Use of current transformers
from other manufacturers can result in instability and/or
unsatisfactory operation.
The 918B includes a provision for changing the current transformer
configuration, should this become necessary. One possible scenario
necessitating this type of change would be as follows:
Example: Measuring 1000 Amps
In order to measure currents of up to 1000 Arms, one could use an
Arbiter Systems Model 09113A 1000:1 clamp-on current
transformer, which must be used in conjunction with a Model
09182A 100:1 current transformer. The resultant combined current
step-down ratio would be 100,000:1. With this combination, the user
would have to reconfigure the 918B from the 1000:1 standard ratio
to the 100,000:1 required by the new combination.
Procedure
1. To change the current transformer configuration, first turn the
unit off.
2. Switch the 918B power ON. There will be a momentary display
of the present ratio setting. The initial default display is "CT:
20A CLAMP-ON".

Operation 13
3. During the time this display is present, press the "HOLD" key.
The next selection will appear, which is "CT: 2A DIRECT". If
this is the desired selection, do nothing; the new value will be
incorporated, and the unit will be ready for use.
4. If another value is desired, press "HOLD" again while the CT
selection display is still present.
5. This key sequence can be continued, as necessary, to scroll
through all of the choices, which are available.
A standard Model 918B is equipped to use the following current
transformers:
20A CLAMP-ON, Standard CT
Calibrated for the standard (Model 09111A) clamp-on 1000:1 20A
current transformer. Note: The calibration constants for this
configuration apply specifically to the 20A clamp-on CT supplied
with, and having the same serial number as the 918B. Use of other
CTs may result in reduced accuracy.
2A DIRECT, Accessory CT
Calibrated for the Arbiter Systems 09182A 100:1 2.0A plug-in
current transformer.
20A DIRECT, Accessory CT
Calibrated for the Arbiter Systems 09182B 1000:1 20A plug-in
current transformer.
1000A CLAMP, Accessory CT
Calibrated for the combination of an Arbiter Systems Model
09113A and Model 09182A. This combination provides clamp-on
measurement capability for currents of up to 1000A.
NOTE When a Model 918B Phase Angle Multimeter is ordered and
shipped from the factory with additional current transformers, a

14 Operation
calibration is performed on the instrument for each of the additional
transformers. When the user selects the appropriate configuration,
the factory-stored calibration constants are automatically applied. If
a current transformer other than one supplied with the unit is used, a
calibration error or performance problem may result. For best
results, always use current transformers supplied by Arbiter
Systems.
Voltage-to-Voltage Measurements
In addition to the current transformer choices, the display will also
indicate "10-750 V ADAPTER". This selection is to be used in
conjunction with the Arbiter Systems Model 09184A Auxiliary
Voltage Adapter, to allow the 918B to perform voltage-to-voltage
phase angle measurements. Refer to Section 3.5 for further
information.
2.2.1.2 Changing the Phase Convention
When used for measurement of the phase angle between a voltage
and current, the 918B will display a value, which is dependent upon
the phase convention that is being employed. There are four
selections available for phase convention.
Lead; 0 – 360
This is the default setting. The displayed value will be a positive
number between 0 and 360, corresponding to the number of degrees
by which the current leads the voltage.
Lag; 0 – 360
The displayed value will be a positive number between 0 and 360,
corresponding to the number of degrees by which the current lags
the voltage.