Aemc instruments JM840A User Manual

AC Current Probe
Model JM840A

User Manual

DESCRIPTION

The JM840A (Catalog # 2110.85) is designed for use in industrial environments. The “squared” jaws
permit multiple conductor or bus bar positioning. The current output makes it the perfect tool for
measurement with DMMs, recorders, power and harmonic meters. The Model JM840A is compatible with
any AC ammeter, multimeter, or other current measuring instrument with an input impedance lower than
5. To achieve the stated accuracy, use the JM840A with an ammeter having an accuracy of 0.75%.

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.

• 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.

INTERNATIONAL ELECTRICAL SYMBOLS

This symbol signifies that the current probe is protected by double or reinforced insulation. Use
only factory 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.

This is a type A current sensor. This symbol signifies that application around and removal
from HAZARDOUS LIVE conductors is permitted.

DEFINITION OF MEASUREMENT CATEGORIES
Cat. IV: For measurements performed at the primary electrical supply (<1000V) such as on primary

overcurrent protection devices, ripple control units, or meters.

Cat. III: For measurements performed in the building installation at the distribution level such as on

hardwired equipment in fixed installation and circuit breakers.

Cat. II: For measurements performed on circuits directly connected to the electrical distribution system.

Examples are measurements on household appliances or portable tools.

RECEIVING YOUR SHIPMENT

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

®

4.72"

(120 mm)

Ø=2.52" (64 mm)

Cable max.

1.97 x 5.31" (50 x 135 mm) or

2.52 x 3.94" (64 x 100 mm)
Bus Bar max.

Red Black

P1 P2

1.89"

(48 mm)

12.40"

(315 mm)

S2S1

ELECTRICAL SPECIFICATIONS

Current Range:

1 to 500A AC continuous cycle
1 to 1000A AC continuous cycle
1 to 1500A AC continuous cycle

Transformation Ratio:

500:1, 1000:1, 1500:1

Output Signal:

2mA AC/A AC (1A at 500A)
1mA AC/A AC (1A at 1000A)

0.66mA AC/A AC (1A at 1500A)

Accuracy and Phase Shift*:
500A RANGE

Primary current 25A 100A 500A

Accuracy % 4% 3% 3%

Phase shift 4° 3.5° 2°

Load Impedance: 5Ω
Overload: 700A for 10 mn
Ampere Second Product: 6 A.s
Accuracy: Per IEC 185-26-27

5 VA Class 3 from 48 to 1000 Hz

1000A RANGE

Primary current 50A 200A 1000A

Accuracy % 3% 2% 1%

Phase shift 3° 1.5° 1°

Load Impedance: 5
Overload: 1400A for 10 mn
Ampere Second Product: 30 A.s
Accuracy: Per IEC 185-26-27

5 VA Class 1 from 48 to 1000 Hz

1500A RANGE

Primary current 75A 300A 1500A

Accuracy % 1.5% 0.75% 0.5%

Phase shift 1.5° 0.75° 0.5°

Load Impedance: 5
Overload: 1800A for 10 mn
Ampere Second Product: 65 A.s
Accuracy: Per IEC 185-26-27

5 VA Class 0.5 from 48 to 1000 Hz

(*Reference conditions: 23°C±3°K, 20 to 85%
RH, 45 to 65 Hz, external magnetic field < 40
A/m, no DC component, no external current
carrying conductor, test sample centered.)

Frequency Range: 30 to 1500Hz; current
derating above 1500Hz for continuous use

Working Voltage: 600V AC
Common Mode Voltage: 600V AC
Open Secondary Voltage: 42V Max.
Influence of Adjacent Conductor:

< 0.005A/A AC

Influence of Conductor in Jaw Opening:

1.5% ± 0.2A on 500:1 range
1% ± 0.2A on 1000:1 range
1% ± 0.2A on 1500:1 range

MECHANICAL SPECIFICATIONS

Operating Temp.: 14° to 122°F (-10° to 50°C)
Storage Temp.: -13° to 176°F (-25° to 80°C)
Influence of Temperature: < 0.1% per 10°K
Jaw Opening: 3.54" (90 mm)

Maximum Conductor Size:

Cable: 2.52"  max. (64mm)
Bus bar: 1.97 x 5.31" (50 x 135 mm)

2.52 x 3.94" (64 x 100 mm)

Envelope Protection: IP 20 (IEC 529)
Drop Test: 1 m (IEC 68-2-32)
Mechanical Shock: 100 g (IEC 68-2-27)
Vibration: 10/55/10 Hz, 0.15 mm (IEC 68-2-6)
Polycarbonate Material:

Handles: 10% fiberglass charged
polycarbonate UL 94 V0

Jaws: ABS UL 94 V2

Dimensions:

4.72 x 12.40 x 1.89" (120 x 315 x 48 mm)

Weight: 2.65 lbs. (1200 g)
Colors: Dark gray handles with red jaws
Output:

Two standard safety banana jacks (4mm)

SAFETY SPECIFICATIONS

Electrical:

Double insulation or reinforced insulation between
primary or secondary and outer case of handle
upon IEC 1010-2-32

Common Mode Voltage:

600V CAT III, Pollution: 2

ORDERING INFORMATION

Current Probe JM840A ................... C at #2110.85

Accessories:

Leads, set of 2, 5 ft. safety (1000V) .. Cat #2111.29

Lead No. 211 for Probe 5A Series

(5 ft, rated 250V) ............................... Cat #2950.06

Pair, safety current leads

(5 ft. retractable, rated 250V) ............ Cat #100.319

OPERATION

Please make sure that you have already read and fully understand the WARNING section on page 1.

Making Measurements with the AC Current Probe Model JM840A

• Connect the black and red terminals to the Ampere AC range of your DMM or current measuring
instrument. Select the appropriate current range (2A AC). Clamp the probe around the conductor to be
tested. If the reading is less than 200 mA, select the lower range until you obtain the best resolution.
Read the value display on the DMM and multiply it by the probe ratio (1000/1). (If reading = 0.592A AC,
the current flowing through the probe is 0.592 mA x 1000 = 592A AC).

• For best accuracy: carefully center the conductor inside the probe jaw, avoid if possible, the proximity of
other conductors which may create noise.

Tips for Making Precise Measurements

• When using a current probe with a meter, it is important to select the range that provides the best
resolution. Failure to do this may result in measurement errors.

• Make sure that probe jaw mating surfaces are free of dust and contamination. Contaminants cause air
gaps between the jaws, increasing the phase shift between primary and secondary. It is very critical for
power measurement.

MAINTENANCE:

Warning

• For maintenance use only original replacement parts.

• To avoid electrical shock, do not attempt to perform any servicing unless you are qualified to do so.

• To avoid electrical shock and/or damage to the instrument, do not get water or other foreign agents
into the probe.

Maintenance

To ensure optimum performance, it is important to keep the probe jaw mating surfaces clean at all times.
Failure to do so may result in error in readings. The following is the recommended procedure for cleaning
the probe jaws: Use a very fine sand paper (fine 600) to avoid scratching the jaw, then gently clean with a
soft oiled cloth.

REPAIR AND CALIBRATION

You must contact our Service Center for a Customer Service Authorization number (CSA#). This will
ensure that when your instrument arrives, it will be tracked and processed promptly. Please write the CSA#
on the outside of the shipping container.

Chauvin Arnoux

®

, Inc. d.b.a. AEMC® Instruments

15 Faraday Drive  Dover, NH 03820 USA
[phone] (Ext. 360) • [phone] (Ext. 360) • [e-mail]

(Or contact your authorized distributor)

NOTE: All customers must obtain a CSA# before returning any instrument.

TECHNICAL AND SALES ASSISTANCE

If you are experiencing any technical problems, or require any assistance with the proper use or
application of this instrument, please contact our technical hotline:

[phone] (Ext. 351) • [phone] (Ext. 351) • [e-mail]

LIMITED WARRANTY

The current probe is warranted to the owner for a period of 2 years from the date of original purchase
against defects in manufacture. This limited warranty is given by AEMC® Instruments, not by
the distributor from whom it was purchased. This warranty is void if the unit has been tampered with,
abused or if the defect is related to service not performed by AEMC® Instruments.

Full warranty coverage and product registration is available on our website at:
www.aemc.com/warranty.html.

Please print the online Warranty Coverage Information for your records.

99-MAN 100063.v7 02/18