Nthytronic Group iRTUe I/O Expansion Module

3.2 Relay Output (DO)

Maximum quantity: 16 channels (2 outputs per group, shared isolation)

Contact type: dry contact (passive)

Isolation voltage: 6 kVrms between coil and contact

Breaking ability:

250 Vac: 8 A (resistive)

30 Vdc：8 A

110 Vdc：0.3 A

220 Vdc：0.12 A

3.3 DC Analog Input (AI)

Maximum quantity: 16 channels (2 inputs per group)

Range options: 4-20 mA (± 20% adjustable), ± 10 Vdc

Accuracy: better than 0.15% after calibration

Isolation: 2.5 kVrms

3.4 Communication Analog Input (AC)

Configuration: 3 voltage channels+3 current channels

Voltage range: 110 Vac (other ranges can be customized)

Current range: 1-5 A

Measurement parameters: voltage, current, phase, frequency, harmonics

Connection method and time synchronization

4.1 Communication Interface

IRTUe provides two ways to connect to the main station:

Dual Ethernet ports (RJ45 or ST/SC fiber 100Base FX): Supports IEC 61850 GOOSE or Modbus TCP. Two ports can be configured for independent communication or redundant mode.

Serial EXP422 port: used to connect iRTU or iGW series devices, using Modbus RTU protocol.

4.2 Time synchronization

To ensure the accuracy of event timestamps and the coordination of GOOSE messages, iRTUe supports the following synchronization methods:

NTP (Network Time Protocol): Obtaining time through Ethernet

EXP422 client: Retrieve time from main station device

The accuracy of time synchronization directly affects the quality of fault recording and SOE (sequence of events recording). In applications that use GOOSE for interlocking, the time difference between each I/O module needs to be controlled within 1ms, and iRTUe can meet this requirement.

Engineering application scenarios

5.1 Load Shedding

In case of power system failure or insufficient power supply, it is necessary to quickly cut off secondary loads to protect critical loads. Traditional solutions rely on hard wiring and PLC scanning cycles, which often result in longer response times. By utilizing iRTUe's GOOSE communication (<3ms), the main station RTU can subscribe in real-time to overload or low-frequency signals from various feeder IEDs and immediately trip the corresponding circuit breaker through iRTUe's output relay. This flexible wiring method is not only fast, but also easy to modify strategies.

5.2 Circuit breaker interlock

In double busbar or bridge type wiring, complex electrical interlocking needs to be established to prevent misoperation of isolation switches. Through GOOSE, the state sharing between IEDs in each interval is achieved. iRTUe collects the position signal of this interval and publishes it, while subscribing to the state of adjacent intervals. After logical judgment, it locks or allows the operation. Compared to traditional hard wiring, GOOSE interlocking greatly reduces the amount of cable laying and maintenance costs.

5.3 Renovation of old substations

Many old stations' main control units (RTUs) do not support IEC 61850, but their I/O points are insufficient. IRTUe can be connected to the old RTU through Modbus serial port or Ethernet, and the newly added I/O signals can be provided to the master station in the form of Modbus registers. At the same time, the master station can also control the output of iRTUe through Modbus. This' plug and play 'approach avoids the high cost of replacing the main station.

5.4 Distributed I/O Expansion

When the monitored devices (such as switchgear and transformers) are scattered in a large area, an iRTUe can be installed locally at each location, forming a ring or star network through fiber optic Ethernet. The central station realizes centralized monitoring of all I/O through GOOSE. Fiber optic communication solves the problems of long-distance electrical signal attenuation and electromagnetic interference.

Mechanical specifications and environmental adaptability

Dimensions: 173 mm (height) x 78.4 mm (width) x 137 mm (depth)

Protection level: IP30 (suitable for indoor switchgear installed on DIN rails)

Working temperature: -25 ℃ to+70 ℃, meeting standards such as IEC 60068-2-1/2/14/30

Vibration and Shock: Complies with IEC 60068-2-6 and IEC 60068-2-7

MTBF：177, 000 hours (approximately 20 years)

Power selection

Wide range type (W): 32-250 Vdc, isolated 2.5 kVrms

Low voltage type (24): 19.5-60 Vdc, isolated 2.5 kVrms

In substations, 110 Vdc or 220 Vdc operating power supplies are typically used to directly supply power to iRTUe without the need for additional power conversion.

Standard Compliance and Certification

IRTUe follows multiple international standards to ensure safety and performance in the power environment:

EMC standards: IEC 61000-6-4 (emission), IEC 61000-6-5 (immunity), and IEC 61000-4-2 to -4-29 sub tests

Product safety: IEC 60950-1

Protection relay standards: IEC 60255-5, IEC 60255-22

Environmental classification: IEC 61850-3 (Environmental requirements for substation communication networks and systems)

Telecommunications port: EN 55022

These certifications mean that iRTUe can be installed in harsh electromagnetic environments near primary equipment such as switchgear and CT/PT rooms without the need for additional shielding.

Configuration and Debugging Tools