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 close the circuit breaker. The Inrush Limiter never interferes with the manual closing operation.

Figure 4-1

Functional Explanation

Item Function
Voltage Input The secondary voltage of the VT for the system voltage (primary side of the circuit breaker for the primary side of the transformer) and transformer voltage (primary or secondary side of the transformer) is input to the control unit via an input converter.
Control Input Receives an external control signal and inputs it into the control unit.
Output of command for closing the circuit breaker Receives a command for closing the circuit breaker from the control unit and outputs it to the external device (circut breaker).
Output of status information Outputs information about unit status and alarms to external devices.
Display of status information Displays information about unit status and alarms.
Touch panel Displays infpmation about operation history of a circuit breaker and alarm monitoring.
Arithmetic part Performs arithmetic operation and control. It consists of a power unit. CPU unit. DI/O unit and A/D unit.
Maintenance PC It provides a LAN connection to a PC intended for adjusting the interface with the controller and maintenance work.

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

General Specifications:

The following table gives the general specifications of the Inrush Limiter.
Operation Unit Control Unit
Part no. T1-2□□ IL-I0-DC110V/DC125V
Mounting method Rack or panel moment
Outer dimension
318 × 266 × 360
(not including projections such as terminal blocks)
318 × 133 × 360
(not including projections such as terminal blocks)
Surface treatment Silver colored anodized aluminum
Weight [kg] 9 7
Power Supply Power supply from the I/O unit(24VDC) 100VDC(90-120V),200W
(For other power supply voltage, please contact us.)
CPU CPU: Atom E3845 1.91GHz
Calendar backup battery life: 10 years
Touch panel 5.7inch(QVGA)
Display colors : 65,536
Backlight service life 50,000 hours or more
Touch panel service life: 1 million times or more
Communications Ethernet 100Base-T or above for
communication with a maintenance PC.
(Other communication function requests, please contact us.)
Cooling method Natural cooling
Ambient temperature and humidity -20℃ to 60℃(no freezing permissible)and 20% to 90%RH(no condensation permissible)
Environment Np harmful smokes or gases, salty gases, explosive gases, water drops or vapor.
excessive dust or powder, excessive vibration or impact, or heat convection obstructions are permissible.
Withstand voltage* 2000VAC, 1 minute,
(Collective grounding of input terminals)
*Except 24VDC circuits.


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 set up the Inrush Limiter.
Figure 4-5
No.ItemGroupDescriptionElectrical specification

I/O Signals:

The following table describes the input and output signals.
1 Control power Power Input the control power of 110/125VDC for this unit. 110VDC(90-120V),200W
2 System voltage Analog input Breaker primary side VT three-phase voltages to be supplied.
3-phase line voltage 110V,50/60Hz
VT load 0.1 VA or less.
3 Transformer voltage Breaker secondary side VT voltages (transformer HV-side or LV-side VT voltages) to be supplied.
3-phase line voltage 110V,50/60Hz
4 Trip signal Digital input Add a current relay to the final stage trip coil of the circuit breaker and connect the relay to this unit.
Input the 1a signal or the circuit breaker pallet contact.
No-voltage contacts(1a).
Contact input rating:
110/125VDC,20mA or more.
5 Close signal Signal for final stage operation of closing the circuit breaker.
6 The palette contacts of the associated breaker Auxiliary contacts of the breaker to be supplied.
7 Write Protect “ON” Circuit breaker primary-side auxiliary contact. No-voltage contacts(1b).
Contact input rating:
110/125VDC,20mA or more.
8 Alarm reset Momentary-switch contact for resetting operation. No-voltage contacts(1a).
Contact input rating:
110/125 VDC,20mA or more.
9 Device enable/disable switch Momentary-switch contact for the enabling/disabling operation.Use it when remote operation is required. No-voltage contacts
(2a, or 1a+ 1b).
Contact input rating:
110/125VDC, 20mA or more.
10 System fault detection To detect a system fault, a separate relay available for this purpose is required. For further details please contact us. No-voltage contacts(1a).
Contact input rating:
20mA or more.
11 Frequency switching(optional) Switching the power frequency between 50 and 60 Hz. For further details please contact us.
12 Ttansformer connection switching(optional) Switching between Y and △ connections for the transformer. For further details please contact us.
13 Command for closing Digital output Outputs the command for closing the circuit breaker. Transistor output
Switching capacity
110/125VDC,max. 7A
14 Device enable/disable status Outputs the enabled/disabled state of the device, it can be used for display purpose/ Use it when the remote display is required. Relay output
Contact capacity
125VDC, max. 0.3A
110VAC, max. 2A
15 Ready Contact is closed with “Ready” on.
16 Alarm Contact is closed with the device fault detected.

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-□) 2 Banks (Model: IL-EC04-□) Cabinet with the front door (Model: IL-EC01-1) Build to order (Model: IL-ECX-□)
Cabinet Cabinet Cabinet We offer to 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 the 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 work 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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