Fully Compensated, Closed-loop
Fiber Optic High Current Measurement
Advanced Accuracy Diagnostics (A2D) continuously
monitors system operation and performance to enhance
measurement confidence. A2D notifies user of specific
installation problems, developing problems and faults. A2D
even records events for subsequent analysis and root cause
investigation and is available via digital connection.
Technical Overview
LKCO represents a significant breakthrough in high current
measurement. Advanced optical technology senses the phase
shift in light caused by the magnetic field from the bus current
when it is routed around a current carrying bus via fiber optics.
LKCO utilizes a unique, patented “fully compensated”
closed-loop system, developed over 8 years of lab and field
experience, to ensure long-term performance. LKCO achieves
this by putting the entire system ( light source, opto-electronics,
fiber optics and measurement output signals ) under complete
closed loop control which automatically compensates for any
sensitivity, gain, drift or zero point change.
2) The two linearly polarized light waves are converted to
circular polarization before traveling around the bus, reflecting off
the end of the fiber and returning along the same path.
The bus magnetic field creates an optical
phase shift due to the Faraday effect. Because
the two light waves are polarized in opposite
directions, the shifts are in opposite directions.
Other conditions, such as vibration, also
create an optical shift but affect the two light
signals in the same direction, therefore not
changing the “measurement” shift.
3) The two light waves return to the opto-electronics where
phase shifts are measured for a 'raw' measurement signal
LKCO is particularly well suited to measure process bus
currents in electro-chemical and industrial processes including
aluminum, chlorine, copper, manganese, titanium and zinc for
process efficiency and control purposes
Key Features
Superior, rejection of external influences. Permits
installation on compact and geometrically complex bus work.
No need for DynAmp Bus Analysis or exact positioning to
optimize performance.
Excellent Low Current Performance thanks to true bidirectional operation and near perfect integration of the bus
magnetic field.
Extremely compact and light-weight. Designed to be
“bus bar mounted”. Eliminates additional support and
protection structures. Compact modular head allows
installation with less than 20cm of bus clearance
Patented Closed-Loop “Full Compensation” places the
entire system (light source, opto-electronics, fiber optics and
even measurement outputs) under closed loop control to
automatically compensate for long term changes.
DynAmp : 3735 Gantz Road, Grove City, Ohio, USA
Polarized light is split into two linearly polarized light waves.
4) Patented closed-loop full compensation
accurately nulls this shift electromagnetically in
the same medium that sensed the bus current.
This automatically compensates for any gain,
sensitivity and zero point change or long term drift in the entire
system ( light source, opto-electronics, fiber optics and
measurement output signal ).
Formerly known as Halmar and LEM DynAmp, High Current Systems
D_LKCO_b Aug. 09
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Fully Compensated, Closed-loop,
Fiber Optic High Current Measurement
Physical Configuration
Input :
( Subject to change without notice )
Bus Current
to +/- 600 kA full scale
110% of F.S. measurement
Infinity without damage
Measurement Performance (applies from 10% to 110% of F.S.):
Measurement accuracy
±0.1% of measurement
±0.02% of measurement
±0.1% of full scale
Measurement Outputs : Uni-directional or bi-directional
10mV / kA or 1V FS
1mV / kA or 1V FS
Optional : Low-level current
High-level voltage
Digital / network
Digital display
Metering Unit
Compensation Module
Measurement Head
61cm w x 77 h x 54 d
44cm w x 39 h x 17 d
Modular, sized to bus
(10cm x 10cm cross-sec)
Measurement Head Mounting Configurations
Standard :Low Level Shunt Voltage Feedback Current (5V max burden)
< 100kA
> 100kA
Metering Unit to Compensation Module Cabling
DynAmp supplied cabling : 30m standard
Connectors at Metering Unit
4mA/kA (250000:1)
Wall / Other Structure
Bus Corner
0/4…20mA full scale
0 to +/- 10V FS
0 to 10kHz full scale
ModBus or ProfiBus
Internal or remote
95…264VAC@47…63Hz or 100…264VDC
350VA w/o environmental options
Isolation ( Hi-Pot tested at 60Hz )
Head to output / chassis
Mains supply to output
Mains or Output to chassis
6.0kVAC for 1 minute
1.5kVAC for 1 minute
1.5kVAC for 1 minute
Measuring Head
Compensation Module
Metering Unit
-40º to 70ºC
-40º to 70ºC
-10º to 40ºC*
-40º to 70ºC
-40º to 70ºC
-40º to 70ºC
*Metering Unit requires fan option from 30º to 40ºC
or air conditioning option for over 40ºC ambient,
requires heater option below -10ºC
Humidity (non-condensing)
DynAmp : 3735 Gantz Road, Grove City, Ohio, USA
0 to 85%
0 to 60%
Bus Suspended – OPTIONAL
Formerly known as Halmar and LEM DynAmp, High Current Systems
Bus Bracket – OPTIONAL
D_LKCO_b Aug. 09
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Fully Compensated, Closed-loop,
Fiber Optic High Current Measurement
Frequently Asked Questions
How difficult is the LKCO to install and commission?
Due to the delicate nature of the LKCO components
before they are assembled into their finished form on-site,
DynAmp highly recommends utilizing one of our technicians in
the installation and commissioning process.
The LKCO is quite lightweight eliminating the need for
hoists, cranes, etc. Two people can easily move all of the
LKCO components, assemble and position the head structure,
place the measurement fiber in the head structure, connect
everything together and switch on. The measurement head
structure size can be easily adjusted on site with hand tools to
provide a perfect fit.
Once switched on, the LKCO Advanced Accuracy
Diagnostics checks the electrical, fiber and optical
connections and subsystems identifying and specifically
reporting any problems found. In addition, with the proper
data connection, DynAmp can access the LKCO remotely to
check the system operation.
If a DynAmp commissioning technician is utilized, he will
also check the performance of the LKCO after installation
using DynAmp’s portable Opti-Cal system.
How close / far from the bus must the head be installed?
The LKCO is very flexible in this regard. Generally, as
long as the measurement head and sensing fiber encircle the
bus, its exact positioning does not matter. For example, if the
installation requires that the head be tilted or angled around
the bus, this has no effect on system performance.
Can fiber length between the compensation module and
metering unit be changed in the field?
Yes, the method is the same as cutting and re-splicing
standard telecom fiber. This requires some specialized
equipment and training. In most cases, we suggest this be
done by DynAmp personnel or by utilizing a certified
subcontractor that is already doing this in fiber-optic
telecommunications applications.
If the fiber assembly is damaged, how can this be fixed?
Standard single-mode fiber is used to connect the optoelectronics to the compensation module. This is standard
telecom type fiber. If damaged, it can be repaired in the field
by splicing in replacement fiber or cutting out a damaged
section and splicing it back together as noted above.
The measurement fiber in the head is highly specialized.
If damaged, it must be returned together with the
compensation module to DynAmp for repair. The entire
assembly can be easily placed in a standard shipping box.
There is no need to return the head structure or the metering
DynAmp : 3735 Gantz Road, Grove City, Ohio, USA
What diagnostics are included?
The LKCO Advanced Accuracy Diagnostics ( A2D )
monitors a wide variety of system parameters to provide users
with measurement confidence and notify them of any
developing problems or failures. A2D monitors both the optoelectronics as well as the fiber optic circuit in this regard and
provides local LED indication, relay output for remote
indication and event recording capability to capture any
intermittent problems for subsequent analysis. Once notified,
users can view and analyze detailed information on a PC via a
user-friendly graphic interface. This can be performed locally
by user personnel or remotely over network connections. If a
connection is provided by the user, DynAmp can also access
this function remotely to assist without having to travel to the
How and how often should the LKCO be calibrated?
The patented closed-loop compensation of the LKCO,
similar to our LKP systems, effectively locks calibration.
There are no normal calibration ‘adjustments’. The only way
that calibration can change is if a technical problem develops.
The system’s Advanced Accuracy Diagnostics continuously
monitors the system and notifies operators if a problem is
detected. Understanding the importance of the data, DynAmp
still recommends that calibration be checked every 3 years on
systems installed on the main process bus bar.
Thanks to the compact, light-weight aspects of LKCO,
this is quite easy. The customer can simply remove and ship
the compensation module with the measurement fiber to
DynAmp for calibration on our highly accurate test stand. ,
DynAmp can organize a rental system if a suitable backup
signal is not available to run the process during that time.
Is there a simple on-site calibration check?
As with our LKP systems, the LKCO can be checked in
the field using a specialized reference system. In the past,
DynAmp checked installed LKP systems with another
specially calibrated reference LKP system mounted on the
same bus. While effective, this was logistically difficult due to
the size and weight of the reference LKP system.
Understanding this, DynAmp has developed a special
version of our LKCO technology to be used as portable
calibration system. This lightweight, compact and portable
‘Opti-Cal’ system allows DynAmp personnel to quickly and
easily perform calibration checks on installed LKCOs as well
as our other systems including LKP.
Formerly known as Halmar and LEM DynAmp, High Current Systems
D_LKCO_b Aug. 09
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Fully Compensated, Closed-loop,
Fiber Optic High Current Measurement
Standard System Includes
Modular head structure for bus-bracket, bus-corner
and wall head mounting
Complete fiber assembly with compensation module
including 30 to 50 meters of Interconnection cabling
Metering Unit for wall mounting
Operator / installation manual
Calibration result data tables and graphs
2 year warranty
Weather resistant shipping packaging
0/4…20mA Measurement Output Signal
Specify Item Number 044445
0…10V Measurement Output Signal
Specify Item Number 044880
0…10kHz Measurement Output Signal
Specify Item Number 044800
Additional 1V Full Scale voltage output signal (only
available if ‘standard’ voltage output is 1 or 10mV / kA)
Specify Item Number on worksheet BEN083
Digital Bus Communications
Floor Stand for Metering Unit cabinet
Provides ability to mount Metering Unit enclosure as a
free-standing unit.
Compensation Module Pedestal
Spare Compensation Module w/ Fiber Circuit
Spare Optical sub-rack for Metering Unit
Specify Item Number 045045
Spare Power sub-rack for Metering Unit
Specify Item Number 044591
Extended Burn-In :
Extended burn-in periods can be ordered in 24 hour
increments. ( 4 hours standard )
Contact DynAmp
3.5 digit LED Current Display
In Metering Unit (AC) : Specify Item Number 044446
In Metering Unit (DC) : Specify Item Number 045179
Remote mounting (AC) : Specify Item Number 043618
Remote mounting (DC) : Specify Item Number 045180
Extended Interconnection Cable
Additional cabling between Compensation Module and
Metering Unit for requirements over 30m.
Suggested Support Services
Metering Unit Cooling Fan ONLY for AC mains
Thermostat controlled cooling fan to extend high
temperature operating capability from 30ºC to 40ºC
Metering Unit Heating ONLY for AC mains
Thermostat controlled heating to extend low
temperature operating capability from -10ºC to -40ºC.
Metering Unit Cooling Fan AND Heating for AC
Metering Unit Air Conditioning
Active air-conditioning to extend high temperature
operating capability above 40ºC.
Specify Item Number 044875 for 115VAC mains
Specify Item Number 044876 for 230VAC mains
( Can not be powered by DC mains )
Specify Item Number 045043
Specify Item Number 044873 for 115VAC mains
Specify Item Number 044874 for 230VAC mains
Specify Item Number 044878
Specify Item Number 044453 for 115VAC mains
Specify Item Number 044454 for 230VAC mains
Measurement Head Bus Bar Suspension Kit
Utilizes reinforced fiberglass cross members to
suspend Measurement Head around the bus bar
Specify Item Number 045077
Specify Item Number 044451 for 115VAC mains
Specify Item Number 044452 for 230VAC mains
Specify Item Number 044989 additional in meters
Specify Item Number 044514
Specify Item Number 044455
Modbus (RTU) : Specify Item Number 044448
Modbus (TCP) : Specify Item Number 045152
Profibus : Specify Item Number 044449
Measurement Head Bus Bar Bracket Kit
Utilizes aluminum brackets, mounted to the bus bar, to
hold the Measurement Head around the bus bar
DC Mains Option
Enables LKCO system to operate from VDC Mains
( Environmental options require AC Mains )
Extended Warranty for LKCO systems < 100kA:
Adds 24 month periods to the standard 24 months.
For LKCO < 100kA specify Item Number 099993
For LKCO > 100kA specify Item Number 099994
On-Site Commissioning: Factory trained technicians and
specialized equipment on-site to verify correct
installation and operation during start-up.
Calibration: Experienced service technicians with specially
adapted calibration equipment are available to verify
proper operation and validate your system
measurement performance to internationally traceable
standards on-site or at DynAmp.
Required Ordering Information
All orders require completion of LKCO Worksheet BEN083 to
be completed regarding the following factors
Bus bar and area details for head size and
installation determination
Head/Compensation and Metering Unit locations for
Head design and cable length determination
Environmental details regarding head/compensation
location and metering unit location for any required
heating or cooling.
NOTE : Delivery lead-time can not be confirmed until
acceptable BEN083 is received by DynAmp and
customer approves subsequent head design.
Specify Item Number 044877
DynAmp : 3735 Gantz Road, Grove City, Ohio, USA
Formerly known as Halmar and LEM DynAmp, High Current Systems
D_LKCO_b Aug. 09
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