System Configuration

The figure on the right shows the system configuration of the Inrush Limiter. The Inrush Limiter receives the manual close signal of the circuit breaker for the transformer bank, and controls the phase timing at which to actually close the circuit breaker. The Inrush Limiter never interferes with the manual closing operation.

Figure 4-1

Functional Explanation

Item Function
Voltage Input Processing This circuit references the source voltage or transformer voltage via the VT (instrumentation transformer) and converts it (110VAC to 5 VAC) for input to the Inrush Limiter.
Control Signal Input Processing This circuit receives the VT voltage and other input signals, and inputs them to the Inrush Limiter.
Controller The Controller performs calculations and log processing. It controls the indicators and provides an interface to the PC for maintenance.
Breaker Closing Signal Output Processing This circuit outputs the close signal that is output from the Inrush Limiter to the circuit breaker.
Status and Alarm Output Processing This circuit outputs status signals about the Inrush Limiter to the customer’s equipment.
PC for Maintenance A LAN jack is provided for connecting a PC to make adjustments and perform other maintenance on the Controller.

Unit Specifications

Appearance: The main unit is designed from two chassis components per bank.
■ The Operation Unit has the following controls and indicators on the front panel. All controls are designed to be simple and intuitive.
  • Data readout LCD
  • Status and alarm indicators
  • Control mode selector
  • Write lock switch
  • Alarm reset button
■ The rear panel has terminals for connections with the customer’s equipment. ■ The rear panel has terminals for connections with the customer’s equipment. ■ The Control Unit houses the controller for the Inrush Limiter. The front panel has a communications port that is used to set and service the Controller. ■ The rear panel has a power supply connector, control power switch, and terminals for connection with the customer’s equipment. ■ The units are installed by making cutouts in the panel and fastening with four M5 screws. ■ Make sure to leave space at the rear of the unit for wiring and servicing.
Figure 4-2
Figure 4-3
Figure 4-4

General Specifications:

The following table gives the general specifications of the Inrush Limiter.
Operation Unit Control Unit
Model Number IL-OU100 IL-CU100
Mounting System Rack or panel
Outline Dimensions W x H x D [mm] 318 × 266 × 360 The Operation Unit and Control Unit are the same size. (Protruding parts such as terminal blocks are not included.)
Paint Color Black (Munsell N1.5)
Weight [kg] 12 12
Power Supply Voltage Supplies power from the Control Unit. 100 VDC (90 to 120 VDC), 40 W
Indicators LCD Panel, 20 characters x 4 lines w/ backlight -
Communications - Supports a PC for maintenance Ethernet100Base-T or higher
Cooling System Air cooled
Ambient Temperature and Humidity 0 to 50°C (no freezing), 20 to 90% (no condensation)
Ambient operating conditions Avoid installation in areas where toxic, explosive, or otherwise hazardous smoke or gases exist. Also avoid areas subject to excessive dust, particulate matter, vibration, or shock. Make sure there are no obstructions to the flow of heated air.
Dielectric Voltage 2000 VAC for one minute, (all input terminals to ground).
Other services Planning consultation, customer-specific requirements, panel production, factory acceptance testing Unit installation, wiring works, on-site testing Maintenance and inspections, Software Tool, communications cables PC for maintenance, inspections, and servicing


The following diagram outlines the connections with the customer’s equipment.

Connections with Customer’s Equipment

Connect wiring from the customer’s substation control panel.

Unit to Unit Connections

Use the special cable supplied with the Inrush Limiter to connect the Operation Unit and the Control Unit.

Connecting a PC for Maintenance

A LAN port is available on the front panel of the Control Unit. A specially designed application program allows you to setup the Inrush Limiter.
Figure 4-5
No.ItemGroupDescriptionElectrical specification

I/O Signals:

The following table describes the input and output signals.
1 Control voltage source Control voltage source Station DC-source voltage to be supplied. DC110V, 40W
2 Power system voltages Analog inputs Breaker primary side VT three phase voltages to be supplied. Voltage across three-phases 100 VAC, load 0.1 VA 50Hz or 60Hz
3 Transformer voltages Breaker secondary side VT voltages (transformer HV-side or LV-side VT voltages) to be supplied.
4 The palette contacts of the associated breaker Digital inputs Auxiliary contacts of the breaker to be supplied. No-voltage contacts(1a1b).
5 [On] breaker manual closing signal Breaker closing signal from the breaker DC110V
6 [Off] breaker manual tripping signal Breaker tripping signal from the breaker
7 On/off state selection switch Selection switch of the on or off states of the equipment No-voltage contacts (1a)
8 Closing signal Digital outputs Breaker closing timing control signal DC110V
9 On/off state signal Status output of the on or off states of the equipment No voltage contact (1a) : rating DC30V,2A
10 Ready state signal Ready state indication
11 Breaker operation unconfirmed signal Indication to show no-return state of the breaker operating signal
12 Voltage abnormal alarm Indication to show abnormal states of VT voltages
13 Control output abnormal alarm Indication to show abnormal state of signal output
14 Functional abnormal alarm Indication of abnormal states of the functional unit

Installation Procedures

Construction and Installation

The Inrush Limiter is designed as a modular unit that is easy to install or remove in a control panel. It can be installed in the substation control panel, or in a stand-alone cabinet.
■ The units are constructed from a case and modular base (contents). The modular base slides out of the case. ■ The units are connected by a special cable with connectors, and inputs and outputs are wired to the customer’s equipment via terminals. ■ All connectors and terminals are located on the rear panel of the modular base. The terminals are plug-in style connectors. ■ The modular base is easy to remove. Simply unplug the connectors and remove the four screws in the front panel.
Figure 4-6

Upright Cabinets

The Inrush Limiter is available as stand-alone units or built-in upright cabinets. The cabinets are available in the following types.
4 Banks (Model: IL-EC04-4) 2 Banks (Model: IL-EC04-4) Cabinet with front door (Model: IL-EC01-1) Build to order (Model: IL-ECX-*)
Cabinet Cabinet Cabinet We offer build to order models according to customer specifications.
- Frame with four mounting banks (maintenance access at front and rear)- 700 x 2300 x 450 mm (W x H x D) (Rack and panel nameplate not included.) - Frame with two mounting banks (maintenance access at front and rear)- 350 x 2300 x 450 mm (W x H x D) (Rack and panel nameplate not included.) - Frame with one mounting bank (maintenance access at front)- 700 x 2000 x 600 mm (W x H x D) (Rack and panel nameplate not included.)


The Inrush Limiter features an HMI (Human Machine Interface) for easy and intuitive operation and settings. You use the LCD panel to operate the Inrush Limiter, and a PC with the specially designed Software Tool installed to for adjustments and maintenance.

LCD panel

The LCD panel on the front panel of the Operation Unit displays the residual fluxes when the transformer is de-energized, the optimum timing at which to re-energize it, and actual data, such as time and phase angle.

Software Tool

The supplied PC application, the Software Tool, allows you to perform the following.
  • Parameter settings
  • Effectiveness graphs
  • Operation logs
  • Manually controlled operations

Supplied Parts

The Inrush Limiter comes with various parts that are useful for installation, wiring, test operation, and inspections.

Attached connecting cable (0.5m length)

This is for connection of two unit modules.

Software tool

Software tool
The application software for operation and maintenance works (CD)are attached as the standard accessory.

PC for maintenance work (Hardware:Option)

Maintenance PC
PC for the operation and maintenance works with LAN cable.


Kodensya provides a wide range of services, from evaluation of the inrush current in existing equipment, to after-sales service. Here is a list of what we can offer.
  • Installation consulting
  • Unit manufacture and sales
  • Installation work and on-site testing
  • Regular inspections, readjustment work, failure repairs
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