ABB IT94-3 HESG440310R2 HESG112699/B System Control / Servo / Static Relay
ABB IT94-3 (HESG440310R2) is a specialized System Control or Servo Module primarily utilized in the ABB Procontrol P13 and Master control systems.
The part numbers HESG440310R2 and HESG112699/B designate its specific electronic assembly and hardware revision level.
1. Introduction
The IT94-3 is a high-performance control module designed for precise processing within industrial automation systems.
It is often described as a servo or static relay module, meaning it is capable of executing complex control algorithms for motor positioning,
speed regulation, or high-speed protection logic (such as Static DMT relaying). It bridges the gap between digital control logic and precision field actuators.
2. Technical Parameter Table
| Parameter | Specification |
| Model Number | IT94-3 |
| Primary Part Number | HESG440310R2 |
| Sub-Assembly No. | HESG112699/B |
| Module Type | System Control / Servo / Static Relay |
| Power Supply | 24 V DC (Nominal range: 18V–30V DC) |
| Power Consumption | Max 10 Watts |
| Operating Temp | -5°C to +45°C (Standard) / Up to 60°C (Extended) |
| I/O Support | Analog, Digital, and Pulse signals |
| Weight | Approx. 0.3 kg to 1.0 kg (depending on housing) |
| Connectivity | Supports Ethernet, Serial, and Proprietary Bus |
3. Related Models
IT94-1 / IT94-2: Earlier versions with lower processing speeds or reduced I/O density.
IW93-2: Analog interface module often used for signal conditioning alongside the IT94-3.
70PR05: A central processor module that often supervises the IT94-3 in a P13 rack.
HESG440310R1: An earlier revision of the R2 hardware assembly.
4. Product Advantages and Features
High-Speed Processing: Equipped with optimized logic for real-time control, essential for servo-motor and high-speed protection applications.
Flexible Signal Handling: Compatible with a variety of signals including pulse-width modulation (PWM) and pulse-train outputs for motion control.
Robust Hardware: Built to withstand the harsh electromagnetic environments of power plants and refineries (HESG military-grade standards).
Hot-Swappable: Designed to be replaced in a powered rack (system-dependent), minimizing maintenance downtime.
Integrated Diagnostics: Features front-panel status indicators to identify logic faults, communication errors, or power issues.
IT94-3 HESG440310R2
5. Application Cases
Motion Control: Precise positioning for robotic arms, CNC machinery, and automated assembly lines.
Power Grid Protection: Functions as a static DMT (Definite Minimum Time) relay for protecting electrical circuits from overcurrent.
Turbine Regulation: Managing the high-speed feedback loops required for steam or gas turbine governor control.
Medical Equipment: Used in large-scale medical imaging or therapeutic devices requiring highly reliable servo control.
6. Installation and Maintenance
Installation:
Slot Alignment: Slide the module into the subrack guides, ensuring the backplane connector is fully seated before tightening the front screws.
Wiring: Use shielded, twisted-pair cables for signal inputs to prevent interference from high-power drive cables.
Addressing: Verify any hardware DIP switches or software station IDs are set to match the existing system configuration.
Maintenance:
Annual Calibration: For servo applications, periodic calibration of the analog/pulse feedback loop is recommended to ensure long-term accuracy.
Dust Management: Ensure the rack’s cooling fans are operational; the IT94-3 can generate up to 10W of heat, which must be dissipated to prevent component aging.
Spare Strategy: As these modules are critical for “active” control, keep a pre-configured spare (matching the HESG revision) for rapid replacement in the event of a fault.