Omega Products HHM72 Installation Manual

Where Do I Find Everything I Need for

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OL

DC

ON

ZERO

600V CAT III - 1500A

!

150A

1500A

OFF

OUTPUT:
1500 A: 1 mV/A
150 A: 10 mV/A

HHM75

AC/DC CURRENT PROBE

®

http:/www.omega.com

e-mail:

[e-mail]

Model HHM72
Model HHM75

AC/DC Current Probes

WARRANTY/DISCLAIMER

.

d

OMEGA ENGINEERING, INC. warrants this unit to be free of defects in materials and workmanship for
a period of 13 months from date of purchase. OMEGA Warranty adds an additional one (1) month
grace period to the normal one (1) year product warranty to cover handling and shipping time. This
ensures that OMEGA's customers receive maximum coverage on each product.

If the unit should malfunction, it must be returned to the factory for evaluation. OMEGA's Customer
Service Department will issue an Authorized Return (AR) number immediately upon phone or written
request. Upon examination by OMEGA, if the unit is found to be defective it will be repaired or replaced
at no charge. OMEGA's WARRANTY does not apply to defects resulting from any action of the
purchaser, including but not limited to mishandling, improper interfacing, operation outside of design
limits, improper repair, or unauthorized modification. This WARRANTY is VOID if the unit shows
evidence of having been tampered with or shows evidence of being damaged as a result of excessive
corrosion; or current, heat, moisture or vibration; improper specification; misapplication; misuse or other
operating conditions outside of OMEGA's control. Components which wear are not warranted, including
but not limited to contact points, fuses, and triacs.

OMEGA is pleased to offer suggestions on the use of its various products. However, OMEGA
neither assumes responsibility for any omissions or errors nor assumes liability for any
damages that result from the use of its products in accordance with information provided by
OMEGA, either verbal or written. OMEGA warrants only that the parts manufactured by it will be
as specified and free of defects. OMEGA MAKES NO OTHER WARRANTIES OR
REPRESENTATIONS OF ANY KIND WHATSOEVER, EXPRESSED OR IMPLIED, EXCEPT THAT OF
TITLE, AND ALL IMPLIED WARRANTIES INCLUDING ANY WARRANTY OF MERCHANTABILITY
AND FITNESS FOR A PARTICULAR PURPOSE ARE HEREBY DISCLAIMED. LIMITATION OF
LIABILITY: The remedies of purchaser set forth herein are exclusive and the total liability of
OMEGA with respect to this order, whether based on contract, warranty, negligence,
indemnification, strict liability or otherwise, shall not exceed the purchase price of the
component upon which liability is based. In no event shall OMEGA be liable for consequential,
incidental or special damages.

CONDITIONS: Equipment sold by OMEGA is not intended to be used, nor shall it be used: (1) as a
"Basic Component" under 10 CFR 21 (NRC), used in or with any nuclear installation or activity; or (2) in
medical applications or used on humans. Should any Product(s) be used in or with any nuclear
installation or activity, medical application, used on humans, or misused in any way, OMEGA assumes
no responsibility as set forth in our basic WARRANTY/ DISCLAIMER language, and additionally,
purchaser will indemnify OMEGA and hold OMEGA harmless from any liability or damage whatsoever
arising out of the use of the Product(s) in such a manner.

RETURN REQUESTS/ INQUIRIES

Direct all warranty and repair requests/inquiries to the OMEGA Customer Service Department. BEFORE
RETURNING ANY PRODUCT(S) TO OMEGA, PURCHASER MUST OBTAIN AN AUTHORIZED
RETURN (AR) NUMBER FROM OMEGA'S CUSTOMER SERVICE DEPARTMENT (IN ORDER TO
AVOID PROCESSING DELAYS). The assigned AR number should then be marked on the outside of
the return package and on any correspondence.

The purchaser is responsible for shipping charges, freight, insurance and proper packaging to prevent
breakage in transit.

FOR WARRANTY RETURNS, please have the following
information available BEFORE contacting OMEGA:

1. P.O. number under which the product was
PURCHASED,

2. Model and serial number of the product under
warranty, and

3. Repair instructions and/or specific problems
relative to the product.

OMEGA's policy is to make running changes, not model changes, whenever an improvement is
possible. This affords our customers the latest in technology and engineering.

OMEGA is a registered trademark of OMEGA ENGINEERING, INC.
© Copyright 1996 OMEGA ENGINEERING, INC. All rights reserved. This document may not be copied,

photocopied, reproduced, translated, or reduced to any electronic medium or machine-readable form, in
whole or in part, without prior written consent of OMEGA ENGINEERING, INC.

FOR NON-WARRANTY REPAIRS, consult
OMEGA for current repair charges. Have the
following information available BEFORE
contacting OMEGA:

1. P.O. number to cover the COST of the repair,

2. Model and serial number of product, and

3. Repair instructions and/or specific problems
relative to the product.

OMEGAnetSM On-Line Service:

http://www.omega.com

Internet e-mail: [e-mail]

Servicing North America:

USA: One Omega Drive, Box 4047

ISO 9001 Certified Stamford, CT 06907-0047

Tel: [phone] FAX: [phone]
e-mail: [e-mail]

Canada: 976 Bergar

Laval (Quebec) H7L 5A1
Tel: [phone] FAX: [phone]
e-mail: [e-mail]

For Immediate Technical or Application Assistance:

USA and Canada: Sales Service: 1-800-826-6342 1-800-TC-OMEGA

Customer Service: 1-800-622-2378 / 1-800-622-BEST
Engineering Service: 1-800-872-9436 / 1-800-USA-WHEN
TELEX: 996404 EASYLINK 62968934 CABLE: OMEGA

Mexico and Tel: (95) 800-TC-OMEGA

SM

FAX: [phone]

Latin America: En Espanol: [phone] ext: 2203

e-mail: [e-mail]

SM

SM

SM

Servicing Europe:

Benelux: Postbus 8034,1180 LA Amstelveen, The Netherlands

Czech Republic: Ostravska 767, 733 01 Karvina

France: 9, rue Denis Papin, 78190 Trappes

Germany/Austria: Daimlerstrasse 26, D-75392 Deckenpfronn, Germany

United Kingdom: 25 Swannington Road, P.O. Box 7, Omega Drive,

150 9002 Certified Broughton Astley, Leicestershire, Irlam, Manchester,

It is the policy of OMEGA to comply with all worldwide safety and EMC/EMI regulations that apply
OMEGA is constantly pursuing certification of its products to the European New Approach Directives
OMEGA will add the CE mark to every appropriate device upon certification.

The information contained in this document is believed to be correct but OMEGA Engineering, Inc
accepts no liability for any errors it contains, and reserves the right to alter specifications without notice.

WARNING: These products are not designed for use in, and should not be used for, patient connecte
applications.

Tel: [phone] FAX: [phone]
Toll Free in Benelux: 06 0993344 e-mail: [e-mail]

Tel: [phone] FAX: [phone]
e-mail: [e-mail]

Tel: [phone] FAX: [phone]
Toll Free/France: 0800-4-06342 e-mail: [e-mail]

Tel: [phone] FAX: [phone]
Toll Free in Germany: 0130 11 21 66
e-mail: [e-mail]

LE9 6TU, England M44 5EX, England
Tel: [phone] Tel: [phone]
FAX: [phone] FAX: [phone]

Toll Free in England: 0800-488-488

e-mail: [e-mail]

Maintenance

War ni ng

· For maintenance use only specified replacement parts.

· Avoid electrical shock: do not attempt to perform any servicing unless

you are qualified to do so.

· Avoid electrical shock and/or damage to the instrument: do not get
water or other foreign agents into the case. Turn the current probe
OFF and disconnect the unit from all circuits before opening the case.

· Also see warning on page 2.

Bat tery Repl acement

· When the probe is turned on, the green LED should light up. If it does
not, replace the 9 V battery. Completely disconnect the probe from the
circuit under test and from the oscilloscope or measuring instrument.
Turn the probe ÒOffÓ, unscrew the battery compartment screw and
remove cover. Replace the battery and put the cover back on.

· Do not replace the battery while the probe is in use.

Cleaning

· Clean the body of the clamp with a cloth lightly moistened with soapy
water. Wipe clean with a cloth moistened with clean water and dry. Do
not use solvent.

Table of Contents

Warning........................................................................................................ 2

International Electrical Symbols.................................................................. 2

Receiving Your Shipment............................................................................ 2

Packaging .................................................................................................... 3

Description ................................................................................................... 3

Specifications............................................................................................... 4

DMM/Display Compatibility ....................................................................... 11

Operating Procedure ................................................................................. 12

Making Measurements with the Models HHM72 and HHM75.......... 12

DC Measurement................................................................................ 12

AC Measurement................................................................................ 13

Indicator Lights.................................................................................... 13

Auto-Off............................................................................................... 13

Operation Examples ........................................................................... 14

Tips for Getting the Best Accuracy .................................................... 17

Typical Response Curves .................................................................. 18

Maintenance .............................................................................................. 20

Warning............................................................................................... 20

Battery Replacement .......................................................................... 20

Cleaning .............................................................................................. 20

20

Warning

These safety warnings are provided to ensure the safety of
personnel and proper operation of the instrument.

· Read the instruction manual completely and follow all the safety
information before attempting to use or service this instrument.

· Use caution on any circuit: Potentially high voltages and currents
may be present and may pose a shock hazard.

· Read the Safety Specifications section prior to using the current
probe. Never exceed the maximum voltage ratings given.

· Safety is the responsibility of the operator.

· NEVER open the back of the instrument while connected to any

circuit or input.

· ALWAYS connect the current probe to the display device before
clamping the probe onto the sample being tested.

· ALWAYS inspect the instrument, probe, probe cable, and output
terminals prior to use. Replace any defective parts immediately.

· NEVER use the current probe on electrical conductors rated
above 600 V in overvoltage category III (CAT III). Use extreme
caution when clamping around bare conductors or bus bars.

Typical Response Cur ves

Model HHM75

Typical Response Curve on the 150 A Range at 50 Hz

0

2

1

0

Error in %

-1

-2

Typical accuracy at 50 Hz: Range 150 A (10 mV/A)

50 100 150

Primary current in amperes

International Electrical Symbols

This symbol signifies that the probes are protected by double or
reinforced insulation. Use only specified replacement parts

when servicing the instrument.

This symbol signifies CAUTION! and requests that the user refer
to the user manual before using the instrument.

Receiving Your Shipment

Upon receiving your shipment, make sure that the contents are
consistent with the packing list. Notify Omega of any missing items. If
the equipment appears to be damaged, file a claim immediately with
the carrier and notify Omega at once, giving a detailed description of
any damage.

219

0.50

0.00

-0.50

-1.00

-1.50

-2.00

-2.50

Error in %

-3.00

-3.50

-4.00

-4.50

Typical Response Curve on 1500 A Range at 50 Hz

101 100 1000 10,000

Primary current in amperes

Typical accuracy at 50 Hz: Range 1500 A (1 mV/A)

Typical Response Cur ves

Model HHM72

Typical Accuracy on the 60 A DC Range

1 10 100

0

-2

-4

-6

-8

Error in %

-10

-12

-14
Primary current in amperes

Typical accuracy at 50 Hz: Range 60 A (10 mV/A)

Typical Accuracy on the 600 A DC Range

1 10 100 1000

2

0

-2

-4

-6

-8

-10

Error in %

-12

-14

-16

-18
Primary current in amperes

Typical accuracy at 50 Hz: Range 600 A (1 mV/A)

18

Packaging

The AC/DC Current Probes Model HHM72 and Model HHM75 include a
9 V battery and user manual.

Description

The Models HHM72 and HHM75 are the newest line of professional
AC/DC current probes. They are designed to the latest safety and
performance standards. Two different hook-shaped jaws are offered,
both permitting the user to ÒpryÓ into or ÒhookÓ onto cables (will accept 2 x
500 MCM) or even smaller bus bars.

Differing from traditional AC transformers, AC/DC current sensing is
often achieved by measuring the strength of a magnetic field created by
a current-carrying conductor in a semiconductor chip using the Hall effect
principle. When a thin semiconductor is placed at right angles to a
magnetic field, and a current is applied to it, a voltage is developed
across the semiconductor. This voltage is known as the Hall voltage,
named after the US scientist Edwin Hall who first reported the
phenomenon. Since the Hall voltage is not dependent on a reversing
magnetic fiels, but only on its strength, the device can be used for DC
measurement. Second, when the
magnetic field strength varies due to
varing current flow in the conductor,
response to change is instantaneous.
Thus, complex AC wave forms may be
detected and measured with high
accuracy and low phase shift. The basic
construction of a probe jaw assembly is
shown Figure 1. (Note: one or two Hall
generators are used depending on the
type of current probe).

Hall

Generator

Figure 1

The electronics and batteries are self-contained in the handles. The
output of the AC/DC probes is 1 mV/A and 10 mV/A. An auto zero push
button ensures rapid and stable zeroing. There is no output filtering ­True RMS with DC components is possible. Phase shift is excellent,
making this series well suited for power and power quality applications.

The Model HHM72 is a portable 400 A AC (600 A peak), 600 A DC
current probe. The unit has proportional mV output for direct readings on
multimeters, recorders, loggers and other instruments accepting banana
plugs. The Model HHM75 is a portable 1000 A AC (1500 A peak), 1500
A DC current probe that accurately measures AC or DC current
waveforms using Hall effect technology.

Both probes have proportional mV output for direct readings on mult
meters, recorders, loggers and other instruments accepting banana plugs.

3

Iron Core

Air Gap

Conductor

HHM72
Specifications

ELECTRICAL

Current Range:

60 A range:

0.2 to 40 A AC (60 A Peak)

0.4 to 60 A DC

600 A range:

0.5 to 400 A AC (600 A Peak)

0.5 to 600 A DC

Output Signal:

10 mV/A on 60 A range
1 mV/A on 600 A range

HHM75
Specifications

ELECTRICAL

Current Range:

150 A Range:

0.2 to 100 A AC (150 A Peak)

0.4 to 150 A DC

1500 A Range:

0.5 to 1000 A AC (1400 A Peak)

0.5 to 1500 A DC

Output Signal:

10 mV/A on 150 A range
1 mV/A on 1500 A range

Tips for Getting the B est A ccur acy

The Models HHM72 and HHM75 are capable of measuring DC and
low frequency currents over a wide range. Here are some key
considerations for getting the most accuracy from your display
instrument:

· When using the Models HHM72 and HHM75 with a DMM or other
meter, it is important to select the range that provides the best
resolution.

· Make sure that probe jaw mating surfaces are free of dust and
contamination.

· Beware of short-circuit currents. Large in-rush DC currents (which
can occur when power is first applied in a circuit) and large high­current transients may cause varying degrees of residual readings. If
in doubt of a particular reading, remove the probe from the
conductor under test and check to see that the display device
returns to zero. If not, it will be necessary to rezero the probe.

Accuracy and Phase Shift*:

60 A Range:

0.5 to 40 A: 1.5% reading ± 0.5 A
40 to 60 A DC only: 1.5% reading

Phase Shift:

45 to 65 Hz 10 to 20 A: £ 3¡
20 to 40 A: £ 2¡

600 A Range:

0.5 to 100 A: 1.5% reading ± 1 A
100 to 400 A: 2.0% reading
400 to 600 DC only: 2.5% reading

Phase Shift:

45 to 65 Hz 10 to 100 A: £ 2¡
100 to 400 A: £ 1.5¡

Overload:

2000 A DC and 1000 A AC
continuous up to 1 kHz

*Reference conditions: 18¡ to 28¡C, 20 to 75% RH, external magnetic field <40
A/m, no DC component, no external current carrying conductor, test sample
centered, 1 MW £100 pF load, zero adjustment prior to measurement [DC only]
DC to 65 Hz. Battery voltage 9 V ± 0.1 V.

Accuracy and Phase Shift*:

150 A Range:

0.5 to 20 A: 1.5% reading ± 0.5 A
20 to 100 A: 1.5% reading
100 to 150 A DC only: 2.5% reading

Phase Shift:

45 to 65 Hz 10 to 20 A: £ 3¡
20 to 100 A: £ 2¡

1500 A Range:

0.5 to 100 A: 1.5% reading ± 1 A
100 to 800 A: 2.5% reading
800 to 1000 A: 4% reading
1000 to 1400 DC only: 4% reading.

Phase Shift:

45 to 65 Hz 10 to 200 A: £ 2¡
200 to 1000 A: £ 1.5¡

4 17

Operation Examples

HHM72 Specs

HHM75 Specs

Measuring the AC Component of an (AC+DC) Waveform for the
Model HHM75

· Conductor carrying 2.5 A DC + 900 A AC

· Voltmeter placed in AC volts mode

· Voltmeter displays 900.0 mV with probe in the 1500 A (10 mV/A) range

900 A AC

OL

DC

ON

900.0MV

ACV

COM

DCV

+

ZERO

600V CAT III - 1500A

!

150A

1500A

OFF

OUTPUT:
1500 A: 1 mV/A
150 A: 10 mV/A

HHM75

AC/DC CURRENT PROBE

®

Cont.

Noise:

60 A Range:
DC to 1 kHz £ 8 mV
DC to 5 kHz: £ 12 mV

0.1 Hz to 5 kHz: £ 2 mV

600 A Range:
DC to 1 kHz £ 1 mV
DC to 5 kHz: £ 1.5 mV

0.1 Hz to 5 kHz: £ 500µV

Rise and Fall Time:

60 A Range:
£ 100µs from 10 to 90% Vout

600 A Range:
£ 70µs from 10 to 90% Vout

MECHANICAL

Humidity Influence:

10 to 90% RH @ reference
temperature £ 0.5%

Jaw Opening:

1.2Ó (31 mm)

Maximum Cable Diameter:

One 1.18" (30 mm) or two 0.95"
(24 mm) or two bus bars 1.2 x

0.4" (31.5 x 10 mm)

Dimensions:

8.8 x 3.82 x 1.73"
(224 x 97 x 44 mm)

Weight:

15 oz (440 g)

Cont.

Overload: 3000 A DC and 2000 A
AC continuous up to 1 kHz

Noise:

150 A Range:
DC to 1 kHz: £ 8 mV
DC to 5 kHz: £ 12 mV

0.1 Hz to 5 kHz: £ 2 mV

1500 A Range:
DC to 1 kHz: £ 1 mV
DC to 5 kHz: £ 1.5 mV

0.1 Hz to 5 kHz: £ 500µV

Rise and Fall Time:

150 A Range:
£ 100µs from 10 to 90% Vout

1500 A Range:
£ 70µs from 10 to 90% Vout

MECHANICAL

Humidity Influence:

10 to 90% RH @ reference
temperature £ 0.1%

Jaw Opening: 1.55Ó (40 mm)

Maximum Cable Diameter:

One 1.5" (39 mm) or one bus bar

1.96 x 0.49 (50 x 12.5 mm) or
Two 0.98" (25 mm) or two bus
bars 1.96 x 0.19" (50 x 5 mm)

Dimensions: 9.31 x 3.82 x 1.73"

(236.5 x 97 x 44mm

Weight: 16 oz (480 g)

16 5

Common Specifications (HHM72 &

HHM75)

ELECTRICAL

Frequency Range: DC to 10 kHz at -3 dB

Load Impedance: >100 kW/100 pF

Insertion Impedance: 0.39 mW @ 50 Hz, 58 mW @1000 Hz

Working Voltage: 600 Vrms

Common Mode Voltage: 600 Vrms

Influence of Adjacent Conductor:

< 10 mA/A at 50 Hz at 23 mm from the probe

Operation Examples

Measuring the DC Component of an (AC+DC) Waveform for the
Model HHM72

· Conductor carrying 300 A DC + 25.0 A AC

· DMM placed in DC volts mode

· DMM displays 300.0 mV with the probe in the 600 A (10 mV/A) range

Influence of Conductor in Jaw Opening:

0.5% reading (DC to 440 Hz)

Battery: 9 V alkaline (NEDA 1604A, IEC 6LR61) recommended, 6LF22

Low Battery: Green LED when battery voltage ³ 6.5 V

Battery Life: Approx. 50 hours with alkaline battery

Overload Indication:

Red LED indicates input greater than the selected range

Auto-Off:

10 minutes (may be disabled at power-up by pressing Zero button
while turning on; green LED blinks three times to indicate that auto-off
is disabled)

MECHANICAL

Operating Temperature Range:

14¡ to 131¡F (-10¡ to 55¡C)

Storage Temperature Range:

-40¡ to 176¡F (-40¡ to 80¡C)

Temperature Influence:

£ 300 ppm/¡K or 0.3%/10¡K

300.0MV

ACV

COM

DCV

+

OL

DC

ON

ZERO

600V CAT III - 600A

!

60A

600A

OFF

OUTPUT:
600 A: 1 mV/A
60 A: 10 mV/A

HHM72

AC/DC CURRENT PROBE

®

300 A DC

Operating Relative Humidity:

10-35¡C: 90% ±5% RH (without condensation)
40-55¡C: 70% ±5% RH (without condensation)

15

Operation Examples

Common Specifications Continued

DC Current Measurement Example for the Model HHM72

· Conductor carrying 25 A DC in the direction of the arrow

· DMM placed in DC volts mode

· DMM displays 250.0 mV with the probe in the 60 A (10 mV/A) range

25 A DC

OL

DC

ON

250.0MV

ACV

DCV

600V CAT III - 600A

!

60A

600A

OFF

ZERO

RH Influence:

10-35¡C: 90% RH at reference
Temperature: £ 0.5% (HHM72)

£ 0.1% (HHM75)

Altitude:

Operating: 0 to 2000 m
Non-operating: 0 to 12,000 m

Zero Adjustment:

Automatic zero (± 10 A) by simple push button increment of 25 to 40 mA.
Red LED goes on at push of button and turns off when zero is reached;
no need to hold button down.

Case protection: IP30 per IEC529

Drop Test:

1.0 m on 38 mm of oak on concrete; test according to IEC 1010

Mechanical Shock:

100 G, test per IEC 68-2-27

Vibration: Test Per IEC 68-2-6,

Frequency Range:

5 to 15 Hz, amplitude: 1.5 mm
15 to 25 Hz, amplitude 1 mm
25 to 55 Hz, amplitude: 0.25 mm

COM

OUTPUT:
600 A: 1 mV/A
60 A: 10 mV/A

HHM72

+

AC/DC CURRENT PROBE

®

Handle: UL94 V0

Jaws: UL94 V0

Color:

Dark gray with red jaws

Output:

Double/reinforced insulated 5 ft. (1.5m) with safety 4 mm banana plug

14 7

Common Specifications Continued

SAFETY

Double insulation or reinforced insulation between primary, secondary
and outer case of handle per IEC 1010-2-032.

· 600 V Category III, Pollution: 2

Electromagnetic Compatibility:

· Susceptibility in accordance with EN 50082-2 and EN 50082-1

· Electrostatic discharge IEC 1000-4-2

Test voltages: 4 kV level 2 in contact, aptitude criteria B
8 kV level 3 in the air, aptitude criteria B

· Radiated Field IEC 1000-4-3 (1995)
With max. interference of 5% of the measurement range:
3 V/m level 3, aptitude criteria A

· Fast transients IEC 1000-4-4 (1995):
Test voltage: 1 kV level 2, aptitude criteria B

· Magnetic fields at the frequency of the network to IEC 1000-4-8 (1995):
With a max. distortion of 0.5 A: 30 A/m 50 Hz level 4, aptitude criteria A

· Emissions in accordance with EN 50081-1

· Radiated emission through the case to EN 55022 (1994): class B

· Conducted emission to EN 55022 (1994): class B

AC Measurement

· Select the appropriate AC mV or V range on the DMM or measuring
instrument.

· The DC zero adjustment is not required when measuring AC current
with a voltmeter that is AC coupled. The DC zero adjustment is
required if you are using a voltmeter that is DC coupled.

· Select the appropriate mV AC or V AC range on the DMM or
measuring instrument.

· Clamp the probe around the conductor (1) to be tested. The display
device should now display the measured conductor current. Apply the
conversion ratio (1mV/A or 10 mV/A) to get the value of the current.

I ndicat or Li ght s: Gr een LED and Red LED

· The green LED (6) indicates that the probe is on and that the battery is
good. The green LED will not light under low battery conditions.
Replace the 9 V battery if the green LED is not lit.

· The red LED (5) indicates a momentary or continuous overload of the
instrument. Readings taken while the red LED is on or flashing should
be considered inaccurate. Momentary or continuous currents
exceeding 60 A peak on the 60 A range or 600 A peak on the 600 A
range for the Model HHM72, and 150 A peak on the 150 A range or
1500 A on the 1500 A range for the Model HHM75 will trigger the red
LED.

Aut o- Of f

· The Models HHM72 and HHM75 have an Auto-off feature which turns
off the instrument after 10 minutes if no control has been used.

· When the probe is switched off by this automatic function, the switch
(7) must first be set to the off position before the probe may be
powered up again.

· Auto-off may be disabled at power-up by the user. Simply press the
auto zero button (4) at the same time as moving the switch (7) from
the OFF position to one of the ranges. The green LED (6) blinks three
times to indicate that the auto-off is disabled.

8 13

Operating Procedure

Making Measur ements wi th the Model s HHM72 and HHM75

· Plug the probe into the display device (e.g., DMM, logger). Note the
polarity of the probe output banana plugs (red = positive [+], black =
negative [-]).

· Select the appropriate range on the display device Note that the
probeÕs outputs are 1 mV/A and 10 mV/A AC or DC. Note the
maximum current capability on 10 mV/A range.

· Turn display device power on. Turn on (7) the probe: the green LED
(6) should be on, and the red LED (5) off. If the green indicator does
not come on or goes off before the probe has operated for 10 minutes,
it is necessary to replace the battery (see ÒBattery Replacement,Ó pg.

20).

· After approximately 10 minutes of operation, if none of the control
buttons has been manipulated power will automatically shut off (see
ÒAuto-OffÓ on pg. 13).

DC Measurement

· Select the appropriate DC mV or V range on the DMM or measuring
instrument.

· ÒZeroÓ the probe. With the probe disconnected from test samples (no
conductor in probe jaw window), press the auto zero button (4). The
red LED (%) comes on for approximately three seconds to indicate
that the probe is zeroing. If the red LED remains lit, this indicates that
zero has not been attained - repeat the zeroing operation.

· For best accuracy, especially on low-level measurement, it is
recommended that you zero the probe before each measurement.

· Clamp the probe around the conductor (1) to be tested. The DMM or
display device should now display the measured conductor current. A
positive reading indicates current flowing in the direction of the arrow
located on the side of the jaw (2). A negative reading indicates current
flow in the opposite direction of the arrow. Apply the conversion ratio
(1mV/A or 10 mV/A) to get the value of the current.

HHM72

Ø =1.18" (30 mm)

Cable max.

Ø =0.95" (24 mm)

Dual Cable max.

5
6

9

8

1. Conductor

2. Jaws

3. Protective non-slip guard

4. Automatic zero DC button

5. Red light (overrange and
incorrect zero adjustment)

6. Green light (on when
battery voltage ³ 6.5 V)

2

1

3

OL

DC

ON

ZERO

600V CAT III - 600A

!

60A

600A

OFF

OUTPUT:
600 A: 1 mV/A
60 A: 10 mV/A

HHM72

AC/DC CURRENT PROBE

®

7

4

7. Three-position range
selection switch:
¥ On/Off
¥ 600 A (1 mV/A)
¥ 60 A (10 mV/A)

8. Lead, 5 ft (1.5 m)

9. Safety banana plug ¯ 4 mm

12

9

HHM75

Ø =1.6" (42 mm)

Cable max.

1.96 x 0.19" (50 x 5 mm)
Dual Bus Bar max.

Ø =0.98" (25 mm)

Dual Cable max.

DMM/Display Compatibility

The Models HHM72 and HHM75 current probes are compatible with any
multimeter, voltmeter or other voltage measuring instrument which has
the following features:

· Input jack that accepts 4 mm safety banana plug

· Range and resolution capable of displaying 1 mV of output per amp of

measured current

· Voltmeter accuracy of 0.3% or better to take full advantage of the
probe accuracy

· Input impedance of 1 MW/100 pF or greater

When the probe is making a measurement, the current-carrying
conductor is not broken and remains electrically isolated from the probe
output. As a result, the probe output common may be either floated
(isolated) or grounded.

1. Conductor

2. Jaws

3. Protective non-slip guard

4. Automatic zero DC button

5. Red light (overrange and
incorrect zero adjustment)

6. Green light (on when
battery voltage ³ 6.5 V)

OL

DC

ON

ZERO

600V CAT III - 1500A

!

150A

1500A

OFF

OUTPUT:
1500 A: 1 mV/A
150 A: 10 mV/A

HHM75

AC/DC CURRENT PROBE

®

Warning: User Safety:

Always use a DMM, voltmeter or other display, appropriately rated for
safety. Also see warning on page 2.

7. Three-position range
selection switch:
¥ On/Off
¥ 1500 A (1 mV/A)
¥ 150 A (10 mV/A)

8. Lead, 5 ft (1.5 m)

9. Safety banana plug ¯ 4 mm

10 11