Iwatsu SS-293S User manual

Rogowski Coil Current Probe
SS-293S/293L/294S/294L
SS-295S/295L/296S/296L
Instruction Manual

Ⓒ2015 IWATSU TEST INSTRUMENTS CORPORATION．All rights reserved．

Contents
Introduction················································································· 1
To ensure Safe Operation ·························································· 1
Warnings····················································································· 2
Cautions······················································································ 5
Checking packed materials························································· 7
Components ··············································································· 7
Management of product······························································ 8
Repair and sending instrument to be repaired ··························· 8
Cleaning of this instrument························································· 8
Chapter 1 Overview ·································································· 9
1.1 Instrument Overview ·············································· 9
1.2 Features·····································································10
1.3 Usage Example··························································11
Chapter 2 Names and Functions of Parts ································12
2.1 Main Unit····································································12
2.2 Names and Functions of Parts of Main Unit··············13
2.3 Rogowski Coil Sensor Part········································14
Chapter 3 Measurement Principle·············································15
3.1 Rogowski Coil Sensor Part········································16
3.2 Main Unit····································································17
Chapter 4 Measurement·····························································18
4.1 Preparation for Measurement····································18
4.2 Measurement Procedure ···········································19
4.3 Before Measurement ·················································21
Chapter 5 Specifications····························································24
5.1 Specifications·····························································24
5.2 Appearance································································26
Contacts

Memo

1
Introduction
◇Thank you for purchasing this instrument of IWATSU TEST
INSTRUMENTS CORPORATION. We hope that you will enjoy it for
years to come.
◇We ask you to thoroughly read this manual before commencing operation
and to keep it at a readily accessible location for future reference.
To ensure Safe Operation
To ensure safe operation of this instrument and to prevent injury to the user
or damage to property, read and carefully observe Warnings and
Cautions in the following sections.
Definition of Warning and Caution as used in this manual
Warning
Incorrect operation or failure to observe a warning may
result in death or serious injury.
Caution
Incorrect operation or failure to observe a caution may
result in bodily injury or damage to the instrument.
Notes
◇Some of the contents of this manual may be modified without notice for
improvements in specifications and functions.
◇Reproduction or reprinting of the contents of this manual without prior
permission from IWATSU TEST INSTRUMENTS CORPORATION is
prohibited.
◇If any question arises about this instrument, contact Iwatsu office or our
sales distributors.
Revision History
◇April 2015: 1st edition
KML099311 A1-711XXX (N)

2
Read the following safety information.
Warnings
Do not use this instrument in an environment with explosive
gases.
Failure to do so may cause an explosion.
If you notice smoke, foul odor, or abnormal noise, immediately
remove this instrument from the target to be measured, power off
the equipment connected with this instrument, and then turn the
POWER switch to the O side to turn off the power to this
instrument.
Continued use under these circumstances may result in an electric shock or
fire. Contact Iwatsu office or our sales distributors for repair. Do not attempt
to repair this instrument yourself.
Never use this instrument for measurement where current or
frequency to be measured exceeds the specifications (refer to
the absolute maximum di/dt in Section 5.1 of this manual).
If the measurement is performed without considering the specifications, an
electric shock or failure may occur.
Never use the coil and sensor cable of this instrument’s input
part for the measurement where voltage exceeds the following
value (the voltage is described on the input part of this
instrument).
An electric shock or failure may occur.
• 10 kVpeak
Use caution not to wet this instrument or allow entry of water or
foreign objects into it.
Continued use under these circumstances may result in an electric shock,
fire, or failure. If water, foreign objects, or other substances enter this
instrument or the instrument is wet with water, immediately remove this
instrument from the target to be measured, power off the equipment
connected with this instrument, and turn the POWER switch to the O side to
turn off the power to this instrument. After that, contact Iwatsu office or our
sales distributors for repair.
Do not use this instrument with wet hands.
If not, an electric shock, fire, or failure may occur.
Do not modify or disassemble this instrument.
Modification or disassembly of this instrument could result in an electric
shock, fire, or failure. Repair of a modified product may be refused. Contact
Iwatsu office or our sales distributors for repair.
[Read the next page.]

3
Read the following safety information. (continued)
Warnings
Use the accessory size AA alkaline batteries or equivalent for this
instrument. Do not use new batteries in combination with old
ones.
Using a battery that does not comply with the above requirements may result
in a fire or failure.
For information on the recommended batteries, refer to Notes 1 and 2 of
Section 5.1 “Specifications.”
Observe the following when handling the coil, sensor cable, or
BNC cable of this instrument.
If not, an electric shock, fire, or failure may occur. Do not use any of the
cables if damaged. Contact Iwatsu office or our sales distributors for repair.
• Do not modify any cable.
• Do not pull on any cable.
• Do not forcibly bend any cable.
• Do not heat any cable.
• Do not twist any cable.
• Do not wet any cable.
• Do not tie any cable in a bundle.
• Do not put heavy objects on any cable.
Do not use this instrument in a highly humid environment where
condensation may occur.
If not, an electric shock, fire, or failure may occur.
[Read the next page.]

4
Read the following safety information. (continued)
Warnings
Avoid the generation of Corona discharge in an environment
where high voltage is applied to the sensor part for a long time.
Depending on the frequency of the applied voltage and installation conditions
of the sensor part, Corona discharge may be generated even when a voltage
lower than resisting voltage is applied to the sensor part. This generation may
lead to degrading the insulating outer sheath, causing an electrical shock,
fire, or failure.
Corona discharge tends to be generated due to electric field concentration.
Take some measures to avoid the generation; for example, keep the sensor
part away from high-voltage parts as far as possible or achieve insulation.
Do not put on this instrument a container that water, medicine,
etc. has entered or a small metallic object.
If not, an electric shock or fire may occur. If this instrument is wet with water, or
metal and other objects enter the instrument, immediately remove this
instrument from the target to be measured, power off the equipment
connected with this instrument, and turn the POWER switch to the O side to
turn off the power to this instrument. After that, contact Iwatsu office or our sales
distributors for repair.
When thunder begins, pull out the power plug of a device to
which this instrument is connected from the outlet. Then, detach
this instrument from the target to be measured, and do not use it.
Lightning may be a cause of an electric shock, fire, or failure.
Do not use this instrument when it has failed.
Using a failed main unit or cable may be a cause of an electric shock or fire.
In the event of a failure, contact Iwatsu office or our sales distributors for
repair.
Turn off the power to the target to be measured before attaching
or detaching the Rogowski Coil Sensor part of this instrument to
or from the target to be measured.
Failure to do so is very dangerous for targets to be measured that use high
voltage and high current.
Insert the end of the Rogowski Coil into the joint hole to fix the
coil with the screw lock. Do not apply a high voltage exceeding
the specifications (refer to Section 5.1 “Specifications”) to the
Rogowski Coil Sensor.
Failure to do so may cause an electric shock, fire, or failure.
The sensor cable cannot be removed because it is integral with
(connected inside of) the main unit. Do not attempt to disconnect
the sensor cable.
Failure to do so may cause an electric shock, fire, or failure.
[Read the next page.]

5
Read the following safety information. (continued)
Cautions
Do not expose to rapidly-changing temperature, mechanical
stress, or impact.
The main unit, coil, sensor and BNC cable will be damaged if exposed to
these. This will be a cause of a failure.
Do not use or store this instrument in a location with direct
sunlight, high temperature, high humidity, or dew condensation.
Operation or storage outside the ratings could result in deformation,
deteriorated insulation, or a failure due to heat. The ranges of operating and
storage temperature and humidity are as follows:
•Operating temperature: 0 to +40C (coil part: −40 to +125C), no dew
condensation
•Operating humidity: 80%RH or less
•Operating altitude: 2000 m or less (at 25C or less)
•Storage temperature: −10 to +60C, no dew condensation
•Storage humidity: 80%RH or less
Do not place this instrument in a location with excessive
humidity or dust.
If not, an electric shock, fire, or failure may occur.
Do not put this instrument in a place exposed to lamp soot or
steam generated by counters, humidifiers, etc.
If not, an electric shock, fire, or failure may occur.
Avoid pulling or bending the Rogowski Coil Sensor part with
excessive force as much as possible. The Rogowski Coil has a coil
structure consisting of an extra-fine wire rod wound tight.
Pulling or bending the Rogowski Coil Sensor part with excessive force may
degrade the specifications of the sensor part due to the change of the coil
structure.
For your safety, when this instrument is not used for a long time,
turn the POWER switch to the O side to turn off the power to this
instrument, and then remove the batteries from this instrument.
[Read the next page.]

6
Read the following safety information. (continued)
Cautions
Use caution when handling this instrument.
The cables of this instrument are long. Take care not to catch your feet or
objects on the cables during measurement and installation.
This instrument can measure high current in high-voltage circuits. Operators
require a basic knowledge of the voltage and current, because using this
instrument will be a cause of human injury depending on the measurement
environment. Before using this instrument, they must obtain the basic
knowledge and receive training on using it safely.
Before moving this instrument, make sure that the coil, sensor,
BNC cable, and other external connection lines are removed.
Failure to do so will damage the cable, causing an electrical shock, fire, or
failure.
To use this instrument, connect it to the ground (output side).
Ground GND terminals of monitoring devices, which are the connection
destination of the output terminal.
Do not energize a target to be measured with nothing connected to the
output terminal. This may be a cause of an electrical shock.
Pay attention to the polarity indication (plus and minus signs)
when placing batteries in this instrument.
A reversely placed battery will result in battery explosion or leakage. This may
cause a fire, injury, failure, or contamination of the surrounding environment.
Do not throw used batteries in the fire.
Batteries thrown in the fire may explode, causing a fire or burn.
For information on disposing of used batteries, refer to “Management of
product” on page 8.
Before transporting this instrument, remove the batteries, house
this instrument in the accessory hard case, and then pack the
housed instrument in the packing material used at the time of
purchase, or the equivalent or better.
This instrument may fail if a large vibration or impact is applied during
transportation, possibly causing a fire. If you do not have a proper packing or
shock-absorbing material for transportation, contact Iwatsu office or our sales
distributors. If transportation is to be handled by a forwarding agent, display
"Contains a precision machine" on each side of the packing box.
For your safety, remove the batteries, monitoring devices, and the
target to be measured from this instrument before maintenance. In
addition, wipe off with a dry cloth when water droplets are
attached.
If not, an electric shock or failure may occur.
We recommend that you contact Iwatsu office or our sales
distributors for periodic inspection and calibration about once a
year.

7
Checking packed materials
When receiving this instrument, check the packed materials while
referring to the following “Components.” If there is a missing item or an
item damaged during transportation, immediately contact Iwatsu office or
our sales distributors.
Components
Main unit ........................... 1
Accessories (See the accessories table below.)
Accessories table
Item
Quantity
Hard case
1
BNC cable
1
Screw driver (flat tip)
1
AA dry battery
4
Instruction Manual (this document)
1

8
Management of product
When disposing of this instrument, it must be recycled or disposed of
properly in accordance with local laws or regulations. When disposing of
it, request a recycling company to dispose of it in accordance with local
laws or regulations.
When disposing of and recycling batteries, separate dry batteries from
rechargeable batteries to observe the following:
•Dry batteries (alkaline and manganese)
Dispose of the batteries in accordance with instructions provided by
local governments.
•Rechargeable batteries (nickel metal-hydride and nickel-cadmium)
Request a recycling company in accordance with local laws or
regulations.
Repair and sending instrument to be repaired
If a failure occurs, send the instrument to Iwatsu office or our sales
distributors.
When sending an instrument to be repaired, clearly write the instrument
name, serial number (in the label on the rear of this instrument),
description of the failure, and the name, division, and telephone number
of the responsible person.
Cleaning of this instrument
To clean this instrument, wipe it gently with a soft cloth moistened with a
small amount of water or mild detergent. Never use solvents such as
benzene, alcohol, acetone, ether, ketones, thinners, or gasoline, as they
can deform and discolor the case.

Chapter 1 Overview
9
Chapter 1 Overview
1.1 Instrument Overview
This instrument is a current probe that uses the Rogowski Coil as a
sensor.
It allows measurement of current in high-voltage and large-current
facilities, such as train inverters, as well as in high-voltage and
large-current applications such as development and maintenance of
infrastructures of the automotive and other industries.
The coil of this instrument detects a change in magnetic flux caused by
the current (target to be measured) flowing through the inside of the coil
that forms a closed loop. The change in magnetic flux generates an
electromotive force in the coil. The electromotive force is proportional to a
differential value of the current. The output (electromotive force) of the
Rogowski Coil is the differential waveform of the current. To detect the
current waveform, the waveform is integrated by the main unit of this
instrument (for details, refer to Chapter 3 “Measurement Principle”).
This series has four models, which differ in sensitivity (mV/A), peak
current (A), low frequency cutoff (Hz), and other specifications. Each
model has two types, which differ in length of the Rogowski Coil; that is,
this series has a lineup of eight models.
Connecting the output part of this instrument and an oscilloscope and
other monitoring devices with the BNC cable allows observation of the
current waveform that flows through a target to be measured.

Chapter 1 Overview
10
1.2 Features
The following describes the features of this instrument.
Target of measurement
•Train inverters etc.
•Development and maintenance of infrastructure facilities of the
automotive and other industries
Easy measurement
Current in facilities (such as switchboards) can be measured easily.
A thin and removable Rogowski Coil (two types of the coils, which
have lengths of 300 mm and 700 mm, respectively, are available,
and the maximum cross sectional diameter of the coil is 8.5 mm)
designed to detect current has the following advantages:
•Wide applications of measurement are possible in any place
•Superior heat resistance and insulation property around the coil
This instrument has the following specifications (for details, refer
to Section 5.1 “Specifications”).
•Frequency bandwidth: fL to 20 MHz [−3 dB] L = 300 mm, fL to 10
MHz [−3 dB] L = 700 mm (fL: Low-Frequency cutoff)
•Peak current: 1.2 kA to 12 kA
(Four models of 1.2 kA, 3 kA, 6 kA, and 12 kA × two types: Total
of eight models)
•Sensitivity accuracy: ±2% (at the center of the coil loop)
•Linearity: ±0.05% of full scale
Power supply
•This instrument operates with the supplied alkaline batteries or
equivalent four AA dry batteries.

Chapter 1 Overview
11
1.3 Usage Example
To measure current using this current probe, place a conductor to be
measured through the coil loop, and detect a change in magnetic flux
caused by the current flowing through the conductor with the Rogowski Coil
as an electromotive force, as shown in the following usage example
(conceptual illustration). The electromotive force (differential value of the
current) passes through the input part of the main unit, and it is integrated by
the integrator of the main unit.
The integrated current value is converted to voltage with a sensitivity (mV/A)
set for each main unit. The converted voltage is output from the output
terminal of the main unit. Inputting the output voltage to an oscilloscope and
other monitoring devices allows observation of the current waveform.
The sensor cable cannot be removed, because it is integral with (connected
inside of) the main unit. Connect the main unit and monitoring devices with the
BNC cable.
Figure 1.1 Usage Example of This Current Probe (Conceptual Illustration)
Conductor to
be measured
Current I
*: The direction of the arrow in the following figure indicates positive
Rogowski Coil Current Probe
(Clip like: Closed loop)
Current waveform is observed
with an oscilloscope (not
included) and other monitoring
devices
BNC cable
Sensor cable
Output
Input
Main unit

Chapter 2 Names and Functions of Parts
12
Chapter 2 Names and Functions of Parts
2.1 Main Unit








Chapter 2 Names and Functions of Parts
13
2.2 Names and Functions of Parts of Main Unit
No.
Name
Description
Reference

POWER switch
Turns this instrument on and off.
This instrument is turned on when this slide
switch is moved to the I side and is turned off
when moved to the O side.
This instrument operates with four AA dry
batteries placed in its back (battery case ).
►Section 4.2

LED lamps
OPERATION
LOW BATTERY
Indicates the operating condition of the power
supply of this instrument. Comes on green when
this instrument is turned on and comes off when
turned off.
Indicates the state of AA dry batteries. This lamp
turns yellow when the batteries are consumed.
Replace them when the lamp lights up yellow.

ZERO ADJ
Used to adjust the zero point of the output .
There is a hole for zero point adjustment on the
side of ZEROADJ. Insert the accessory screw
driver into the hole to perform zero point
adjustment.
►Section 4.2

Input part
The sensor cable (refer to Section 2.3) integral
with the main unit is connected to this part.
►Section 2.1

Output part
BNC output connector.
Outputs the voltage (current waveform) of the
main unit.
►Section 2.1

Battery case
Located on the back of the main unit and used
to house fourAA dry batteries. To open this
battery case, push its lid downward. Place the
batteries in this case while paying attention to
their orientation, and then close the lid.
►Section 2.1

Back label
There is a label placed on the back of the main
unit.
The label describes the following:
• TYPE: One of the eight models, SS-293S/L,
294S/L, 295S/L, 296S/L
• Peak Current: One of the current values that
the above model handles, 1.2 kA, 3 kA,
6 kA, or 12 kA
• Sensitivity: Voltage sensitivity (mV/A) of the
current that the above model handles.
• S/N: 11-digit serial number
►Section 2.1

Chapter 2 Names and Functions of Parts
14
2.3 Rogowski Coil Sensor Part
No.
Name
Description

Rogowski Coil
A coil for detecting the current in conductors to be
measured. Forms a closed loop during measurement.
Covered with an insulating outer sheath for heat resistance
and insulation.

Joint box
The sensor cable is secured to one end so that the
Rogowski Coil forms a closed loop. There is a screw lock
and joint hole to secure the other end of the coil.

Joint hole
A part of the joint box and has a hole to insert the
Rogowski Coil and a screw lock to lock and release the
coil. The one end of the coil can be removed from this
hole by hand by releasing the lock.

Screw lock
A rotary locking mechanism used to lock and release one
end of the Rogowski Coil.

Sensor cable
A coaxial cable used to input the electromotive force
(differential value of the current) that is generated in the
Rogowski Coil to the main unit.




Current direction mark


Chapter 3 Measurement Principle
15
Chapter 3 Measurement Principle
This instrument is designed to measure the current (current waveform) in
conductors to be measured.
It consists of the Rogowski Coil Sensor part and the main unit (integrator).
Sections 3.1 and 3.2 in this chapter describe measurement principles and
functions of each part and are concluded with an explanation of a process of
measuring the current (current waveform).

Chapter 3 Measurement Principle
16
3.1 Rogowski Coil Sensor Part
Figure 3.1 shows that the current I flows through the conductor to be
measured. This section describes the principle of detecting this current by
the Rogowski Coil step by step.
Note)The above figure is a conceptual illustration to explain this measurement principle. The
Rogowski Coil Sensor part is actually covered with the insulating outer sheath. During
measurement, one end of the Rogowski Coil is inserted into the joint hole on the joint box
and locked by the screw lock.
Figure 3.1 Conceptual Illustration of Rogowski Coil
It is assumed that the conductor to be measured is placed inside of the loop
of the Rogowski Coil. A magnetic field is generated around the conductor to
be measured. It moves around the conductor in a clockwise direction in
relation to the current direction (Ampere’s right-handed screw law).
The magnetic field changes with time, because alternating current flows in
the conductor to be measured. In the Rogowski Coil, magnetic flux changes
along the loop. When it changes, an electromotive force is generated and
current flows in the coil by electromagnetic induction.
Provided that the entire length of the wound Rogowski Coil is l, small radius
of the coil turn is r, turn of the coil is N, and current flowing through the coil is
i, the electromotive force generated in the coil is expressed by Equation 3.1:
…… (3.1)
As shown in Equation 3.1, the electromotive force induced in the coil is
determined by the shape and turn of the coil and time differentiation of the
current. Thus, the electromotive force must be integrated to determine the
current.
Conductor to
be measured
Rogowski Coil Sensor part
Returning part
of windings
Signal that is
differential of input
current
Output voltage (V)
(Current waveform)
Main unit
Observation with
an oscilloscope
and other
monitoring devices
Insertion
Current (I)
M
Ma ag gn ne et ti ic c
f
fi ie el ld d
Integrator
Where,
(Permeability of Vacuum)