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Current Probes
User Manual
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ETS-Lindgren L.P. reserves the right to make changes to any product described
herein in order to improve function, design, or for any other reason. Nothing
contained herein shall constitute ETS-Lindgren L.P. assuming any liability
whatsoever arising out of the application or use of any product or circuit
described herein. ETS-Lindgren L.P. does not convey any license under its
patent rights or the rights of others.
© Copyright 2008 by ETS-Lindgren L.P. All Rights Reserved. No part of this
document may be copied by any means without written permission from
ETS-Lindgren L.P.
Trademarks used in this document: The ETS-Lindgren logo is a trademark of
ETS-Lindgren L.P.
Revision Record
MANUAL DESCRIPTION | Part #399297, Rev. A
Revision Description Date
A Initial Release December, 2008
ii |
Page 3
Table of Contents
Notes, Cautions, and Warnings .............................................. vii
1.0 Introduction .......................................................................... 9
ETS-Lindgren Product Information Bulletin ................................................. 10
2.0 Maintenance ....................................................................... 11
Annual Calibration ....................................................................................... 11
Service Procedures ..................................................................................... 11
3.0 Specifications ..................................................................... 13
Model 91197 Series Current Probe ............................................................. 13
Model 91197 Series Physical Specifications ....................................... 13
Model 91197 Series Electrical Specifications ...................................... 14
Model 91550 Series Current Probe ............................................................. 15
Model 91550 Series Physical Specifications ....................................... 15
Model 91550 Series Electrical Specifications ...................................... 15
Model 91550 Series Pulse Power Limits ............................................. 17
Model 93511 Series Current Probe ............................................................. 18
Model 93511 Series Physical Specifications ....................................... 18
Model 93511 Series Electrical Specifications ...................................... 18
Model 93686 Series Current Probe ............................................................. 19
Model 93686 Series Physical Specifications ....................................... 19
Model 93686 Series Electrical Specifications ...................................... 20
Model 94106 Series Current Probe ............................................................. 21
Model 94106 Series Physical Specifications ....................................... 21
Model 94106 Series Electrical Specifications ...................................... 21
Model 94106 Series Pulse Power Limits ............................................. 22
Model 94111 Series Current Probe ............................................................. 23
Model 94111 Series Physical Specifications ....................................... 23
Model 94111 Series Electrical Specifications ...................................... 23
Model 94111 Series Pulse Power Limits ............................................. 24
Model 94430 Series Current Probe ............................................................. 25
Model 94430 Series Physical Specifications ....................................... 25
Model 94430 Series Electrical Specifications ...................................... 25
Model 94430 Series Pulse Power Limits ............................................. 26
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Model 94606 Series Current Probe ............................................................. 27
Model 94606 Series Physical Specifications ....................................... 27
Model 94606 Series Electrical Specifications ...................................... 27
4.0 Principles of Operation ..................................................... 29
Circuit ........................................................................................................... 29
Basic RF Transformer .......................................................................... 30
Sensitivity ..................................................................................................... 31
Model 91197 Series Typical Sensitivity ............................................... 31
Model 91550 Series Typical Sensitivity ............................................... 31
Model 93511 Series Typical Sensitivity ............................................... 32
Model 93686 Series Typical Sensitivity ............................................... 32
Model 94106 Series Typical Sensitivity ............................................... 32
Model 94111 Series Typical Sensitivity ............................................... 33
Model 94430 Series Typical Sensitivity ............................................... 33
Model 94606 Series Typical Sensitivity ............................................... 33
Core Saturation and Intermodulation ........................................................... 34
Transfer Impedance ..................................................................................... 34
5.0 Assembly and Installation ................................................ 37
Equipment Setup to Measure RF Current ................................................... 37
For a Single Conductor ........................................................................ 37
For a Two-Conductor Cable ................................................................ 37
For Multi-Conductor Cables ................................................................. 37
To Evaluate Shielding Effectiveness ................................................... 38
Installation Instructions ................................................................................ 38
Sample Test Configuration .......................................................................... 39
6.0 Operation ............................................................................ 41
Signal Measurement .................................................................................... 42
Signal Injection ............................................................................................ 45
7.0 Typical Data ........................................................................ 47
Model 91197 Series Current Probe ............................................................. 47
Model 91197-1 Transfer Impedance ................................................... 47
Model 91197-1L Transfer Impedance ................................................. 47
Model 91550 Series Current Probe ............................................................. 48
Model 91550-1 Transfer Impedance ................................................... 48
Model 91550-2 Transfer Impedance ................................................... 48
iv |
Page 5
Model 91550-5 Transfer Impedance ................................................... 49
Model 93511 Series Current Probe ............................................................. 50
Model 93511-1 Transfer Impedance ................................................... 50
Model 93511-1L Transfer Impedance ................................................. 50
Model 93686 Series Current Probe ............................................................. 51
Model 93686-1 Transfer Impedance ................................................... 51
Model 93686-8 Transfer Impedance ................................................... 51
Model 94106 Series Current Probe ............................................................. 52
Model 94106-1 Transfer Impedance ................................................... 52
Model 94111 Series Current Probe ............................................................. 53
Model 94111-1 Transfer Impedance ................................................... 53
Model 94111-2 Transfer Impedance ................................................... 53
Model 94430 Series Current Probe ............................................................. 54
Model 94430-1 Transfer Impedance ................................................... 54
Model 94606 Series Current Probe ............................................................. 55
Model 94606-1 Transfer Impedance ................................................... 55
Appendix A: Warranty ............................................................. 57
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vi |
Page 7
Notes, Cautions, and Warnings
Note: Denotes helpful information intended to
See the ETS-Lindgren Product Information Bulletin for safety,
regulatory, and other product marking information.
provide tips for better use of the product.
Caution: Denotes a hazard. Failure to follow
instructions could result in minor personal injury
and/or property damage. Included text gives proper
procedures.
Warning: Denotes a hazard. Failure to follow
instructions could result in SEVERE personal injury
and/or property damage. Included text gives proper
procedures.
| vii
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viii |
Page 9
1.0 Introduction
The ETS-Lindgren Current Probe is a clamp-on RF current transformer that
determines the intensity of RF current present in an electrical conductor or group
of conductors. The current probe is designed for use with electromagnetic
interference (EMI) test receivers or spectrum analyzers, or with any similar
instrument having a 50-ohm input impedance.
Model 93511 Series Current Probe
A current probe provides a way to accurately measure net (common mode) radio
frequency current flowing on a wire or bundle of wires without requiring a direct
connection to the conductor(s) of interest. The probe clamps around the test
conductor which becomes a one turn primary winding; the probe forms the core
and secondary winding of an RF transformer. Measurements can be made on
single-conductor and multi-conductor cables, grounding and bonding straps,
outer conductors of shielding conduits and coaxial cables, and so on.
Introduction | 9
Page 10
This manual includes these ETS-Lindgren current probes:
Model 91197 Series
• 91197-1
• 91197-1L
Model 93686 Series
• 93686-1
• 93686-8
• 93686-8L
Model 94430 Series
• 94430-1
• 94430-1L
Model 91550 Series
• 91550-1
• 91550-1L
• 91550-2
• 91550-2L
• 91550-5
Model 94106 Series
• 94106-1
• 94106-1L
Model 94606 Series
• 94606-1
• 94606-1L
• 94606-6
ETS-Lindgren Product Information Bulletin
Model 93511 Series
• 93511-1
• 93511-1L
Model 94111 Series
• 94111-1
• 94111-1L
• 94111-2
See the ETS-Lindgren Product Information Bulletin included with your shipment
for the following:
• Warranty information
• Safety, regulatory, and other product marking information
• Steps to receive your shipment
• Steps to return a component for service
• ETS-Lindgren calibration service
• ETS-Lindgren contact information
10 | Introduction
Page 11
2.0 Maintenance
Before performing any maintenance,
follow the safety information in the
ETS-Lindgren Product Information
Bulletin included with your shipment.
WARRANTY
Maintenance is limited to external
components such as cables or
connectors.
If you have any questions concerning
maintenance, contact ETS-Lindgren
Customer Service.
Annual Calibration
See the Product Information Bulletin included with your shipment for information
on ETS-Lindgren calibration services.
Service Procedures
For the steps to return a system or system component to ETS-Lindgren for
service, see the Product Information Bulletin included with your shipment.
Maintenance | 11
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12 | Maintenance
Page 13
3.0 Specifications
At the lower frequencies, the signal current I
allowed for maximum power current. When both signal and power
currents are high, their sum should not exceed the given limits.
L model current probes are calibrated down to 20 Hz.
level can be as great as
P
Model 91197 Series Current Probe
MODEL 91197 SERIES PHYSICAL SPECIFICATIONS
Window Diameter: 3.18 cm
1.25 in
Outside Diameter: 8.26 cm
3.25 in
Width: 3.56 cm
1.4 in
Output Connector: Type N
Weight: 0.6 kg
1 lb 5 oz
Impedance: 50 Ω
Specifications | 13
Page 14
MODEL 91197 SERIES ELECTRICAL SPECIFICATIONS
91197-1 91197-1L
Frequency Range
(L Models 20 Hz):
Transfer Impedance
(Nominal):
RF Current Range
(RF CW):
RF Current Range
(Pulse):
Maximum Power
Current
(DC-400 Hz):
10 kHz–8 MHz 20 kHz–8 MHz
0.32 Ω ± 2 dB
10 kHz–1 MHz
100 amps
100 amps
(200 amps with reduced
duty cycle)
350 amps 1000 amps
0.32 Ω ± 2 dB
1 kHz–1 MHz
• >20 kHz–150 amps max
• 10 kHz–166 amps max
• 4 kHz–200 amps max
• 2 kHz–250 amps max
• 1 kHz–400 amps max
• 400 Hz–1000 amps ma
Below 400 Hz the probe is
limited by core saturation
effects at an I
1000 amps
100 amps
(200 amps with reduced
duty cycle)
of
P
Maximum Power
Voltage:
Sensitivity Under
Rated Load:
14 | Specifications
No limitation; subject to adequate conductor insulation
30 microamperes with
1 microvolt sensitivity
receiver and 0.33 ohm
transfer impedance
30 microamperes with
1 microvolt sensitivity
receiver and 0.33 ohm
transfer impedance
Page 15
Model 91550 Series Current Probe
MODEL 91550 SERIES PHYSICAL SPECIFICATIONS
Window Diameter: 3.18 cm
1.25 in
Outside Diameter: 8.89 cm
3.5 in
Width: 7.29 cm
2.87 in
Output Connector: Type N
Weight: 0.6 kg
1.31 lb
Impedance: 50 Ω
MODEL 91550 SERIES ELECTRICAL SPECIFICATIONS
91550-1 91550-2 91550-5
Frequency Range
(L Models 20 Hz):
Transfer Impedance
(Nominal):
RF Current Range
(RF CW):
RF Current Range
(Pulse):
Maximum Power
Current
(DC–60 Hz):
10 kHz–100 MHz 10 kHz–150 MHz 10 kHz–200 MHz
5.0 Ω ± 3 dB
1 MHz–100 MHz
42 amps 2.8 amps 2.3 amps
100 amps 100 amps 100 amps
350 amps 350 amps 350 amps
1.0 Ω ± 2 dB
1 MHz–150 MHz
Specifications | 15
1.0 Ω ± 2 dB
1 MHz–100 MHz
Page 16
Maximum Power
Current
(400 Hz):
Maximum Power
Voltage:
Internal Loading: No Yes No
Rated Ouptut Load
Impedance:
Sensitivity Under
Rated Load:
91550-1 91550-2 91550-5
350 amps,
50 Hz–1500 Hz
No limitation; subject to adequate conductor insulation
50 Ω
50 Ω 50 Ω
0.17 microampere
with 1 microvolt
sensitivity
receiver and
6 ohm transfer
impedance
225 amps 225 amps
1.0 microampere
with 1 microvolt
sensitivity
receiver and
1 ohm transfer
impedance, or
10 mV across
50 ohm load for
0.01 amp signal
1.0 microampere
with 1 microvolt
sensitivity
receiver and
1 ohm transfer
impedance, or
10 mV across
50 ohm load for
0.01 amp signal
16 | Specifications
Page 17
MODEL 91550 SERIES PULSE POWER LIMITS
91550-1 91550-2 91550-5
RF Current
Range (Pulse):
Maximum Power
Current
(L Models Only):
100 amps Pulse signals with
peak currents to
100 amps can be
measured if the
pulse duty cycle
does not exceed:
)
P
)
P
)
P
P
• (2 MHz)
50 amps
• (1 MHz)
60 amps
• (0.5 MHz)
85 amps
• (10 amps I
0.080 Duty
• (30 amps I
0.010 Duty
• (50 amps I
0.003 Duty
• (100 amps I
0.001 Duty
• (60 Hz)
650 amps
• (120 Hz)
650 amps
• (400 Hz)
500 amps
100 amps with
maximum pulse
duty cycle not to
exceed 0.002 for
100 amp signal
)
NA
• (0.2 MHz)
175 amps
• (0.1 MHz)
340 amps
• (0.05 MHz)
650 amps
• (1500 Hz)
140 amps
Specifications | 17
Page 18
Model 93511 Series Current Probe
MODEL 93511 SERIES PHYSICAL SPECIFICATIONS
Window Diameter: 3.18 cm
1.25 in
Outside Diameter: 8.26 cm
3.25 in
Width: 3.56 cm
1.4 in
Output Connector: Type N
Weight: 0.6 kg
1 lb 5 oz
Impedance: 50 Ω
MODEL 93511 SERIES ELECTRICAL SPECIFICATIONS
93511-1 93511-1L
Frequency Range
(L Models 20 Hz):
Transfer Impedance
(Nominal):
RF Current Range
(RF CW):
RF Current Range
(Pulse):
Maximum Power
Current
(DC–60 Hz):
18 | Specifications
10 kHz–30 MHz 20 kHz–30 MHz
1 Ω (0 db) ± 2 dB
100 kHz–10 MHz
100 amps 100 amps
200 amps 200 amps
350 amps 800 amps
1 Ω (0 db) ± 2 dB
100 kHz–10 MHz
Page 19
Maximum Power
Current
(400 Hz):
Maximum Power
Voltage:
Sensitivity Under
Rated Load:
93511-1 93511-1L
350 amps 800 amps
No limitation; subject to adequate conductor insulation
1.0 microampere with
1 microvolt sensitivity
receiver and 1 ohm
transfer impedance
1.0 microampere with
1 microvolt sensitivity
receiver and 1 ohm
transfer impedance
Model 93686 Series Current Probe
MODEL 93686 SERIES PHYSICAL SPECIFICATIONS
Window Diameter: 6.65 cm
2.62 in
Outside Diameter: 13.97 cm
5.5 in
Width: 5.38 cm
2.12 in
Output Connector: Type N
Weight: 2.27 kg
5 lb
Impedance: 50 Ω
Specifications | 19
Page 20
MODEL 93686 SERIES ELECTRICAL SPECIFICATIONS
93686-1 93686-8
Frequency Range
(L Models 20 Hz):
Transfer Impedance
(Nominal):
RF Current Range
(RF CW):
RF Current Range
(Pulse):
Maximum Power
Current
(DC–60 Hz):
Maximum Power
Current
(400 Hz):
Maximum Power
Voltage:
Sensitivity Under
Rated Load:
10 kHz–30 MHz 10 kHz–200 MHz
2.0 Ω ± 2 dB
100 kHz–10 MHz
0 amps–200 amps 0 amps–62 amps
200 amps 62 amps
350 amps 300 amps
350 amps 300 amps
No limitation; subject to adequate conductor insulation
0.5 microampere with
1 microvolt sensitivity
receiver and 2 ohm
transfer impedance
8.0 Ω ± 3 dB
10 MHz–200 MHz
0.125 microampere with
1 microvolt sensitivity
receiver and 8 ohm
transfer impedance
20 | Specifications
Page 21
Model 94106 Series Current Probe
MODEL 94106 SERIES PHYSICAL SPECIFICATIONS
Window Diameter: 3.18 cm
1.25 in
Outside Diameter: 8.26 cm
3.25 in
Width: 3.56 cm
1.4 in
Output Connector: Type N
Weight: 0.43 kg
15 oz
Impedance: 50 Ω
MODEL 94106 SERIES ELECTRICAL SPECIFICATIONS
94106-1
Frequency Range
(L Models 20 Hz):
Transfer Impedance
(Nominal):
RF Current Range
(RF CW):
RF Current Range
(Pulse):
Maximum Power
Current
(DC–60 Hz):
100 kHz–450 MHz
• 2 Ω (6 db) ± 3 dB @ 1 MHz
• 6 Ω (15.5 db) ± 3 dB @ 100 MHz—450 MHz
20 amps
50 amps
200 amps
Specifications | 21
Page 22
Maximum Power
Current
(400 Hz):
Maximum Power
Voltage:
Rated Output Load
Impedance:
Sensitivity Under
Rated Load:
94106-1
200 amps
No limitation; subject to adequate conductor insulation
50 Ω
0.1 microampere with 1 microvolt sensitivity receiver
and 10 ohm transfer impedance
MODEL 94106 SERIES PULSE POWER LIMITS
94106-1 / 94106-1L
RF Current Range
(Pulse):
Maximum Power
Current
(L Models Only):
50 amps
• (DC to 60 Hz) 300 amps
• (DC to 120 Hz) 300 amps
• (DC to 400 Hz) 300 amps
• (DC to 1500 Hz) 300 amps
When both signal and power currents are high, their
sum should not exceed the given limits
22 | Specifications
Page 23
Model 94111 Series Current Probe
MODEL 94111 SERIES PHYSICAL SPECIFICATIONS
Window Diameter: 3.18 cm
1.25 in
Outside Diameter: 8.89 cm
3.5 in
Width: 3.56 cm
1.4 in
Output Connector:
Weight: 0.42 kg
Impedance: 50 Ω
Type N
15 oz
MODEL 94111 SERIES ELECTRICAL SPECIFICATIONS
94111-1 / 94111-1L 94111-2
Frequency Range
(L Models 20 HZ):
Transfer
Impedance
(Nominal):
RF Current Range
(RF CW):
1 MHz–1000 MHz 1 MHz–1000 MHz
• 0.9Ω(-1dB Ω) ±3dB
@1 MHz
• 2.5Ω(8dB Ω) ±3dB
@10 MHz
• 5Ω(14dB Ω) ±3dB
@100 MHz
• 5.6Ω(15dB Ω) ±3dB
@500 MHz
20.0 amps 1.7 amps
1Ω(0dB Ω) ±3dB
@1 MHz–100 MHz
RF Current Range
(Pulse):
50 amps 200 amps
Specifications | 23
Page 24
Maximum Power
Current
(DC–400 Hz):
Maximum Power
Voltage:
Sensitivity Under
Rated Load:
94111-1 / 94111-1L 94111-2
200 amps 200 amps
No limitation; subject to adequate
conductor insulation
0.2 microampere with
1 microvolt sensitivity
receiver and 5 ohms
transfer impedance
1 microampere with
1 microvolt sensitivity
receiver and 1 ohm
transfer impedance
MODEL 94111 SERIES PULSE POWER LIMITS
94111-1 / 94111-1L 94111-2
RF Current Range
(Pulse):
50 amps for duty cycle less
than 0.4
Pulse signals with peak
currents to 200 amps can
be measured if the pulse
duty cycle does not
exceed:
• (10 amps I
• (50 amps I
0.0024 Duty
) 0.06 Duty
P
)
P
Maximum Power
Current
(L Models Only):
24 | Specifications
(DC to 1500 Hz) 300 amps
When both signal and
power currents are high,
their sum should not
exceed the given limits
• (100 amps I
0.0006 Duty
• (200 amps I
0.00015 Duty
NA
)
P
)
P
Page 25
Model 94430 Series Current Probe
MODEL 94430 SERIES PHYSICAL SPECIFICATIONS
Window Diameter: 1.91 cm
0.75 in
Outside Diameter: 5.72 cm
2.25 in
Width: 2.54 cm
1.0 in
Output Connector:
Weight: 0.18 kg
Impedance: 50 Ω
Type BNC
6.5 oz
MODEL 94430 SERIES ELECTRICAL SPECIFICATIONS
94430-1 / 94430-1L
Frequency Range
(L Models 20 Hz):
Transfer Impedance
(Nominal):
RF Current Range
(RF CW):
RF Current Range
(Pulse):
10 kHz–250 MHz
• 6 Ω ± 2 dB @ 10 MHz–250 MHz
• 3 Ω ± 2 dB @ 1 MHz
• 0.6 Ω ± 3 dB @ 100 kHz
• 0.1 Ω ± 3 dB @ 10 kHz
16 amps
70 amps
Maximum Power
Current
(DC–400 Hz):
200 amps
Specifications | 25
Page 26
Maximum Power
Voltage:
Sensitivity Under
Rated Load:
94430-1 / 94430-1L
No limitation; subject to adequate conductor insulation
0.125 microampere with 1 microvolt sensitivity receiver
and 8 ohm transfer impedance
MODEL 94430 SERIES PULSE POWER LIMITS
94430-1 / 94430-1L
RF Current Range
(Pulse):
Maximum Power
Current
(L Models Only):
Pulse signals with peak currents to 70 amps can be
measured if the pulse duty cycle does not exceed:
• (16 amps I
• (25 amps I
• (40 amps I
• (50 amps I
• (70 amps I
) 1.0 Duty
P
) 0.625 Duty
P
) 0.39 Duty
P
) 0.3125 Duty
P
) 0.227 Duty
P
(DC to 1500 Hz) 400 amps
26 | Specifications
Page 27
Model 94606 Series Current Probe
MODEL 94606 SERIES PHYSICAL SPECIFICATIONS
Window Diameter: 12.7 cm
5.0 in
Outside Diameter: 19.81 cm
7.8 in
Width: 5.38 cm
2.12 in
Output Connector: Type N
Weight: 3.18 kg
7.0 lb
Impedance: 50 Ω
MODEL 94606 SERIES ELECTRICAL SPECIFICATIONS
94606-1 94606-6
Frequency Range
(L Models 20 HZ):
Transfer
Impedance
(Nominal):
RF Current Range
(RF CW):
RF Current Range
(Pulse):
Maximum Power
Current
(DC–60 Hz)
(400 Hz):
10 kHz–100 MHz 1 kHz–5 MHz
5 Ω ±4dB
@1 MHz–100 MHz
0 amps–100 amps 0 amps–300 amps
0 amps–100 amps 0 amps–400 amps
350 amps 350 amps
Specifications | 27
1 Ω ±2dB
@10 kHz–5 MHz
Page 28
Maximum Power
Voltage:
Rated Output Load
Impedance:
Sensitivity Under
Rated Load:
94606-1 94606-6
No limitation; subject to adequate
conductor insulation
50 Ω 50 Ω
0.2 microampere with
1 microvolt sensitivity
receiver and 5 ohms
transfer impedance
1 microampere with
1 microvolt sensitivity
receiver and 1 ohm
transfer impedance
28 | Specifications
Page 29
4.0 Principles of Operation
Before connecting any components or
operating the probe, follow the safety
information in the ETS-Lindgren
Product Information Bulletin included with your
shipment.
The current probe is an inserted-primary type of radio frequency current
transformer. When the probe is clamped over the conductor or cable in which
current is to be measured, the conductor forms the primary winding. The
clamp-on feature of this probe enables easy placement around any conductor or
cable.
Circuit
The circuit is that of a radio frequency transformer, as illustrated on page 30.
Because the current probe is intended for clamp-on operation, the primary shown
on page 30 is the electrical conductor in which interference currents are to be
measured. This primary is considered as one turn since it is assumed that the
noise currents flow through the conductor and return to the source by way of a
ground conductor such as a frame, common ground plane, or earth. On some
current probe models the secondary output terminals are resistively loaded
internally to provide substantially constant transfer impedance over a wide
frequency range.
Principles of Operation | 29
Page 30
BASIC RF TRANSFORMER
30 | Principles of Operation
Page 31
Sensitivity
Probe sensitivity in microamperes depends on the sensitivity in microvolts of the
receiving equipment with which it is used. The following tables show the
relationship of receiving sensitivity in microvolts to the overall sensitivity of the
probe and receiver in microamperes. This data is based on the transfer
impedance of each model.
MODEL 91197 SERIES TYPICAL SENSITIVITY
Test Equipment Sensitivity
in Microvolts
4 12.1
2 6.0
1 3.0
0.1 0.3
ZT = 0.33 Ω
MODEL 91550 SERIES TYPICAL SENSITIVITY
Test
Equipment
Sensitivity
in Microvolts
5 1 5 5
2 0.4 2 2
1 0.2 1 1
0.1 0.02 0.1 0.1
91550-1
ZT = 5.0 Ω
91550-2
ZT = 1.0 Ω
91197-1
91550-5
ZT = 1.0 Ω
Principles of Operation | 31
Page 32
MODEL 93511 SERIES TYPICAL SENSITIVITY
Test Equipment Sensitivity
in Microvolts
4 4.0
2 2.0
1 1.0
0.1 0.1
ZT = 1.0 Ω
MODEL 93686 SERIES TYPICAL SENSITIVITY
Test Equipment
Sensitivity
in Microvolts
4 2.0 0.5
2 1.0 0.25
1 0.5 0.125
0.1 0.05 0.0125
93686-1
ZT = 2.0 Ω
93511-1
93686-8
ZT = 8.0 Ω
MODEL 94106 SERIES TYPICAL SENSITIVITY
Test Equipment Sensitivity
in Microvolts
4 0.8
2 0.4
1 0.2
0.1 0.02
32 | Principles of Operation
94106-1
ZT = 5.0 Ω
Page 33
MODEL 94111 SERIES TYPICAL SENSITIVITY
Test Equipment
Sensitivity
in Microvolts
5 1 5
2 0.4 2
1 0.2 1
0.1 0.02 0.1
94111-1
ZT = 5.0 Ω
MODEL 94430 SERIES TYPICAL SENSITIVITY
Test Equipment Sensitivity
in Microvolts
5 0.625
2 0.25
1 0.125
0.1 1.0125
ZT = 6.0 Ω
94111-2
ZT = 1.0 Ω
94430-1
MODEL 94606 SERIES TYPICAL SENSITIVITY
Test Equipment
Sensitivity
in Microvolts
4 0.8 4
2 0.4 2
1 0.2 1
0.1 0.02 0.1
Principles of Operation | 33
94606-1
ZT = 5.0 Ω
94606-6
ZT = 1.0 Ω
Page 34
Core Saturation and Intermodulation
The magnetizing effects of a primary conductor carrying large currents at power
line frequencies can saturate the current probe core material. Core saturation
produces non-linear transforming action and can result in:
• A decrease in the current probe RF output for a given RF current input.
• Modulation of the RF output by the power line frequency.
The specified pulse duty cycle should not be
exceeded or the current probe internal load
resistor (if applicable) may be subject to
damage. The load resistor must also be
protected from excessive line currents.
The influence of intermodulation on the current probe output as measured with
the EMI test equipment is negligible for primary conductor power frequency
currents under 300 amperes. For primary power currents above 300 amperes,
measurements taken by the EMI test equipment generally will not be affected by
intermodulation due to the averaging characteristics for the quasi-peak and peak
functions; the readings will increase with current.
Transfer Impedance
The RF current (IP) in microamps in the conductor under test is determined from
the reading of the current probe output in microvolts (E
probe transfer impedance (Z
Or, in dB:
dBμAE
I
P
34 | Principles of Operation
).
T
IP
S
E
S
Z
T
dBμV Z
) divided by the current
S
dB
T
Page 35
The typical transfer impedance of the current probe throughout the frequency
range is shown in Typical Data on page 47. It is determined by passing a known
RF current (I
developed across a 50-ohm load.
) through the primary test conductor and noting the voltage (ES),
P
E
ZT
S
I
P
Principles of Operation | 35
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36 | Principles of Operation
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5.0 Assembly and Installation
Before connecting any components, follow the
safety information in the ETS-Lindgren
Product Information Bulletin included with your
shipment.
Equipment Setup to Measure RF Current
Standing waves can exist on the test conductor under test at or near
the resonant frequency. Under these conditions, several
measurements taken along the line will provide a complete picture of
the RF current distribution and amplitude.
FOR A SINGLE CONDUCTOR
1. Place the probe jaws around the conductor so that the conductor
passes through the center opening.
2. Lock the jaws together.
FOR A TWO-CONDUCTOR CABLE
• To evaluate the common mode component of the noise current (the
net effect of the currents leaving and returning): Place the probe over
both conductors at the same time.
• To measure the interference current in either conductor separately:
Place the probe over each wire individually.
FOR MULTI-CONDUCTOR CABLES
The probe will measure the net external effects of all the currents in the
conductors that pass through the center of the probe.
Assembly and Installation | 37
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TO EVALUATE SHIELDING EFFECTIVENESS
When placed over shielding conduit, coaxial cable, or ignition shielding, the
probe measures the current flowing on the external surface of the shield.
Installation Instructions
The window (aperture) of the probe will accommodate cables up to the
following maximum outside diameters.
Current Probe Maximum Outside Diameter
Model 91197 Series 1.25 inches
Model 91550 Series 1.25 inches
Model 93511 Series 1.25 inches
Model 94106 Series 1.25 inches
Model 94111 Series 1.25 inches
Model 94430 Series 0.75 inches
Model 93686 Series 2.62 inches
Model 94606 Series 5.0 inches
For greatest accuracy, the conductor under measurement should be
centered in the window of the current probe.
Place the probe around the conductor(s) to be measured and then carefully lock
the probe jaws. Otherwise, inadequate shielding or incorrect air gap will result
and the measurement will not be accurate.
The connecting cable used between the current probe and the EMI test
equipment must have 50-ohm characteristic impedance and matching cable
connectors. The current probe is calibrated for use only with a 50-ohm load.
Therefore, the EMI test equipment must have a 50-ohm input impedance.
Observe precautions regarding minimum bending radius when installing and
using the cable. For long cables and at high frequencies, cable loss may also be
a factor. Use low loss cables and perform cable loss corrections if necessary.
38 | Assembly and Installation
Page 39
The probe rejection of any external pickup from conductors not passing through
the window is better than 60 dB. The presence of very strong magnetic fields will
likely have an effect on probe sensitivity. Do not place the unit close to
permanent magnets or the magnetic field structures of motors or generators.
Sample Test Configuration
Assembly and Installation | 39
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40 | Assembly and Installation
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6.0 Operation
Before connecting any components, follow the
safety information in the ETS-Lindgren
Product Information Bulletin included with your
shipment.
If measuring uninsulated conductors: Use
extreme care when installing the current probe
and taking measurements. If possible,
de-energize the test sample during assembly
and disassembly of the setup. Also, arrange to
center the test conductor in the current probe
window for additional voltage breakdown
protection.
Do not permit the uninsulated current probe
connector and cable connectors to come in
contact with the ground plane or other nearby
conductors. This will prevent possible
measurement error due to ground loops, and
will avoid danger from high voltages.
Ensure that the 50-ohm load is capable of safely
dissipating the incurred power. Should the load
become disconnected, the developed voltage
will be come much greater and may be very
dangerous.
The RF current probe is a broadband RF transformer for use with EMI test
equipment. Radio frequency currents can be measured in cables without
physically disturbing the circuit.
Operation | 41
Page 42
Signal Measurement
OSCILLOSCOPE USE: IN TERMS OF RF AMPERES
1. Standardize the gain of the oscilloscope to correctly read the
voltage (E
2. Divide E
in ohms. The result is the value of the RF signal in terms of amperes in
the test conductor.
Example:
Assume an oscilloscope peak voltage measurement of 5 volts and the
average Z
conductor.
The example is valid providing that the oscilloscope rise time
(T = 0.3/BW) is shorter than RF signal pulse duration. This also applies
to the current probe which has a rise time of about 3 nanoseconds
based on a 100 megahertz bandwidth.
IN TERMS OF dB ABOVE ONE MICROAMPERE AT METER INPUT
(CW CONDUCTED MEASUREMENTS)
) applied to the input terminals.
S
in volts by the average current probe transfer impedance ZT
S
to be 1.06 ohms. Then: 5/1.06 = 4.71 amperes in the test
T
1. Adjust the EMI test equipment for standard gain and make a
measurement of the CW signal (voltage output from the current probe)
in terms of dB above one microvolt. Use procedures outlined in the
EMI test equipment instruction manual.
2. Subtract the transfer impedance of the current probe in dB at the test
frequency from the dB measurement of the previous step. The result is
the value of the conducted CW signal in terms of dB above one
microamp at meter input.
At meter input as used in the MIL-I-26600 and MIL-I-6181D
specifications refers to the current in the test sample lead.
42 | Operation
Page 43
Example:
Frequency is 10.0 kHz; step 1 measurement is 52 dB above
one microvolt. For example, suppose the transfer impedance of the
current probe used in the example was 8.0 dB below one ohm at
10.0 kHz. Then, as outlined in step 2: 52 dB + 8.0 dB = 60 dB above
one microampere at meter input.
IN TERMS OF dB ABOVE ONE MICROAMPERE PER MEGAHERTZ AT
METER INPUT (BROADBAND INTERFERENCE MEASUREMENT)
1. Adjust the EMI test equipment for standard gain and make a peak
measurement of the broadband interference (voltage output from the
current probe) in terms of dB above one microvolt per megahertz. Use
procedures outlined in the EMI test equipment instruction manual.
2. Subtract the transfer impedance of the current probe in dB at the test
frequency from the dB measurement of the previous step. The result is
the value of the broadband interference in terms of dB above
one microamp per megahertz at meter input.
At meter input as used in the MIL-I-26600 and MIL-I-6181D
specifications refers to the current in the test sample lead.
Example:
Frequency is 100 kHz; step 1 measurement is 41 dB above
one microvolt per megahertz. For example, suppose the transfer
impedance of the current probe was 8.0 dB below one ohm at
100 kHz. Then, as outlined in step 2: 41 dB + 8.0 dB = 49 dB above
one microamp per megahertz at meter input.
This result is beyond the limit of 46.2 dB above one microamp per
megahertz.
Operation | 43
Page 44
IN TERMS OF MICROAMPERE IN TEST SAMPLE LEAD
(CW CONDUCTED MEASUREMENTS)
1. Adjust the EMI test equipment for standard gain and make a
measurement of the CW signal (voltage output from current probe) in
terms of microvolts at meter input. Use procedures outlined in the EMI
test equipment instruction manual.
2. Divide the microvolt measurement of the previous step by the transfer
impedance in ohms at the test frequency. The result is the value of
conducted CW signal in terms of microamperes in the test sample
lead.
Example:
Frequency is 3.0 kHz; step 1 measurement is 150 microvolts.
For example, suppose the transfer impedance of the current probe was
0.34 ohms. Then, as outlined in step 2, 150/0.34 = 441.1
microamperes in the test sample lead.
IN TERMS OF MICROAMPERE PER MEGAHERTZ IN TEST SAMPLE LEAD
(BROADBAND INTERFERENCE MEASUREMENT)
1. Adjust the EMI test equipment for standard gain and make a
measurement of the broadband interference (voltage output from
current probe), in terms of microvolts per megahertz at meter input.
Use procedures outlined in the EMI test equipment instruction manual.
2. Divide the microvolt per megahertz measurement of the previous step
by the transfer impedance in ohms at the test frequency. The result is
the value of conducted broadband interference in terms of microamps
per megahertz in the test sample lead.
Example:
Frequency is 10.0 kHz; step 1 measurement is 8000 microvolts per
megahertz. For example, suppose the transfer impedance of the
current probe was 0.39 ohms. Then, as outlined in step 2,
8000/0.39 = 20513 microamps per megahertz in test sample lead.
44 | Operation
Page 45
Signal Injection
Applies to Model 94111 Series only.
Current probes may be used to inject RF currents into test conductors when
performing susceptibility tests. Injection is best accomplished with current probes
that do not have internal loading. Internal loading will absorb part (or most) of the
driving power and can seriously limit the maximum levels of voltage and current
that the current probe can handle as an injection device.
The current probe does not have an internal load and therefore is suited for
signal injection. However, it will be limited by connector voltage rating (500 V)
and by the thermal limit of the coil windings. A maximum continuous injection
current into the current probe coils of 4.2 amps may be used; two or three times
this level may be used for short periods of time. When injecting pulse signals, the
average current should be held within the above limits, and the peak voltage held
below 500 V.
Because of variable circuit impedances, there is no easy way to compute the
RF current that may be injected into the test conductor. The practical way to
determine the injected current is to measure it with a second current probe on the
test conductor. The second current probe can be any model that covers the
frequency range of interest.
Operation | 45
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46 | Operation
Page 47
7.0 Typical Data
Model 91197 Series Current Probe
MODEL 91197-1 TRANSFER IMPEDANCE
MODEL 91197-1L TRANSFER IMPEDANCE
Typical Data | 47
Page 48
Model 91550 Series Current Probe
MODEL 91550-1 TRANSFER IMPEDANCE
MODEL 91550-2 TRANSFER IMPEDANCE
48 | Typical Data
Page 49
MODEL 91550-5 TRANSFER IMPEDANCE
Typical Data | 49
Page 50
Model 93511 Series Current Probe
MODEL 93511-1 TRANSFER IMPEDANCE
MODEL 93511-1L TRANSFER IMPEDANCE
50 | Typical Data
Page 51
Model 93686 Series Current Probe
MODEL 93686-1 TRANSFER IMPEDANCE
MODEL 93686-8 TRANSFER IMPEDANCE
Typical Data | 51
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Model 94106 Series Current Probe
MODEL 94106-1 TRANSFER IMPEDANCE
52 | Typical Data
Page 53
Model 94111 Series Current Probe
MODEL 94111-1 TRANSFER IMPEDANCE
MODEL 94111-2 TRANSFER IMPEDANCE
Typical Data | 53
Page 54
Model 94430 Series Current Probe
MODEL 94430-1 TRANSFER IMPEDANCE
54 | Typical Data
Page 55
Model 94606 Series Current Probe
MODEL 94606-1 TRANSFER IMPEDANCE
Typical Data | 55
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56 | Typical Data
Page 57
Appendix A: Warranty
See the Product Information Bulletin included with your shipment for
the complete ETS-Lindgren warranty.
DURATION OF WARRANTIES
All product warranties, except the warranty of title, and all remedies for warranty
failures are limited to two years.
Product Warranted Duration of Warranty Period
Model 91197 Series Current Probe 2 Years
Model 91550 Series Current Probe 2 Years
Model 93511 Series Current Probe 2 Years
Model 93686 Series Current Probe 2 Years
Model 94106 Series Current Probe 2 Years
Model 94111 Series Current Probe 2 Years
Model 94430 Series Current Probe 2 Years
Model 94606 Series Current Probe 2 Years
Warranty | 57
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