Application Scenarios

Within the reactor protection system of a nuclear power plant,the reliable detection of a”low-low”reactor coolant level is a paramount safety function.A single undetected sensor failure could be catastrophic.The system uses a 2-out-of-3(2oo3)voting architecture with three independent sensor trains.Each sensor’s dry contact signal is fed into a dedicated TOSHIBA DI335H​module,residing in separate,physically isolated safety cabinets.The TOSHIBA DI335H’s role is to convert the 24VDC field signal into a precise,noise-immune logic level for its associated safety controller.Its high channel-to-channel and channel-to-system isolation prevents a fault in one sensor circuit from propagating.During a quarterly test,technicians simulate a sensor activation.The millisecond-level response time of the DI335H​ensures the signal is registered by the controller without delay,and its onboard diagnostic LEDs immediately confirm a healthy input state.This reliable performance underpins the entire safety loop,allowing the protection system to execute a guaranteed,fail-safe shutdown when required,with absolute confidence in the input data.

Parameter

Here are the key technical specifications for the TOSHIBA DI335H​module:

Main Parameters

Value/Description

Product Model​

DI335H

Manufacturer​

Toshiba Infrastructure Systems&Solutions

Product Category​

Digital Input Module(Safety/High-Reliability Grade)

System Compatibility​

TOSMAP Series Safety&Control Systems

Number of Channels​

32 channels(typically arranged in groups of 8 or 16)

Input Type​

Sinking or Sourcing,24 VDC(Dry Contact or Solid-State)

Input Voltage Range​

19.2 to 30 VDC(Wide operating range for stable operation)

On Voltage Level​

Typically≥18 VDC(Recognizes a valid”ON”signal)

Off Voltage Level​

Typically≤5 VDC(Ensures reliable”OFF”state detection)

Input Current​

Approximately 5-10 mA per point(at 24 VDC)

Isolation​

Channel-to-Channel and Channel-to-Backplane Isolation(Prevents fault propagation and ensures signal integrity)

Response Time​

≤5 ms(Fast response for critical shutdown logic)

Diagnostics​

Per-channel status LED,Group fuse monitoring,Health status reporting to controller

Connection​

Removable terminal block or high-density connector

Certifications​

Designed to meet stringent nuclear and industrial safety standards(e.g.,IEC 61508,IEEE)

Technical Principles and Innovative Values

The TOSHIBA DI335H​is engineered not just for function,but for assuredfunction under fault conditions,embodying principles of safety,diagnostics,and longevity.

Innovation Point 1:Defense-in-Depth Isolation Architecture

Unlike standard DI cards,the DI335H​employs a multi-barrier isolation strategy.Each channel group is optically or magnetically isolated from the controller’s logic-side,and channels within a group are also isolated from each other.This architecture,critical for nuclear and high-integrity process applications,ensures that a field-side fault—such as a short to high voltage—is contained and cannot damage the controller or cause erroneous readings on other channels,preserving the system’s overall health and availability.

Innovation Point 2:Intelligent Diagnostics for Proactive Health Management

The module integrates comprehensive diagnostics that go beyond a simple power LED.It typically provides per-channel status indication,group fuse failure detection,and loss-of-field-power sensing.This diagnostic data is reported to the TOSMAP controller,enabling predictive maintenance.For example,a drifting field power supply voltage can be flagged before it causes an input to drop out,allowing for scheduled correction and avoiding a nuisance trip or,worse,a failure to detect a true process demand.

Innovation Point 3:Designed for Extreme Reliability and Long Lifecycles

Components in the TOSHIBA DI335H​are derated and selected for industrial temperature ranges and long-term stability.The design minimizes points of failure and is often conformally coated for protection against humidity and contaminants.This makes it suitable for installation in harsh locations like nuclear auxiliary buildings or offshore platforms,where mean time between failures(MTBF)is measured in decades,not years,aligning with the 40+year lifecycles of the plants it serves.

Innovation Point 4:Seamless Integration with TOSMAP Safety Logic

The module’s firmware and hardware timing are tightly synchronized with the TOSMAP controller’s scan cycle.This deterministic behavior is non-negotiable for safety systems.The DI335H​ensures that input state changes are captured reliably within a known,bounded time window,which is essential for the precise timing analysis required in safety validation(e.g.,calculating Probability of Failure on Demand-PFD).

Application Cases and Industry Value

Case Study:Modernization of a Boiling Water Reactor(BWR)Safety System

A Generation II BWR plant in Europe embarked on a long-term safety system modernization to extend its operational license.A key part was replacing the aging hardwired relay logic for the main steam isolation valve(MSIV)control with a digital safety system based on TOSMAP.The new system required reading dozens of valve limit switch positions,pressure switch statuses,and manual override commands.The TOSHIBA DI335H​was selected as the primary digital input interface due to its certification pedigree and proven in-plant performance in similar applications.

A total of 12 DI335H​modules were installed across three redundant divisions.During factory acceptance testing(FAT),engineers subjected the modules to rigorous electromagnetic interference(EMI)and”dirty”voltage signal tests.The DI335H​modules demonstrated flawless noise immunity,correctly interpreting signals even with significant superimposed electrical noise,a common issue in power plant environments.Post-commissioning,the plant’s I&C manager reported a 60%reduction in troubleshooting time for input circuit faults compared to the old system,directly attributing this to the clear per-channel diagnostics.More importantly,the deterministic performance of the DI335H​contributed to a successful safety system PFD calculation,a critical factor in receiving regulatory approval for the plant life extension.

Related Product Combination Solutions

A complete TOSMAP-based safety or control node utilizing the DI335H​requires several synergistic components:

Safety Controller(e.g.,TOSMAP CPU modules):​The brain of the system.The DI335H​feeds critical process status information to controllers like the TOSMAP SC​or TOSMAP QD​series,which execute the safety or control logic.

Digital Output Modules(e.g.,DO335H):​The companion module.After the controller processes inputs from the DI335H,it commands final elements(solenoids,motor starters)via corresponding high-reliability digital output modules.

Analog Input/Output Modules(e.g.,AI/AO series cards):​For a comprehensive system handling both discrete and analog signals(e.g.,pressure,temperature),these modules work alongside the DI335H.

Power Supply Units(PSUs):​Dedicated,redundant,and often monitored power supplies are required to provide the clean,stable 24VDC field power for the sensors connected to the DI335H.

Communication Modules/Backplanes:​Specialized network interfaces(e.g.,for peer-to-peer safety network communication)and the passive backplane that physically and electrically connects the DI335H​to the controller and other modules.

Termination Units/Field Interfaces:​Often,intermediary termination assemblies(like Toshiba TMC-7​series)are used between the field wiring and the DI335H​to provide additional surge protection,fusing,and test points,enhancing maintainability and protection of the control cabinet electronics.

Installation,Maintenance,and Full-Cycle Support

Installation of the TOSHIBA DI335H​must be performed in strict accordance with plant safety procedures and Toshiba’s engineering guidelines.The module is designed for secure mounting on a standard DIN rail or dedicated backplane within a controlled environment cabinet.Critical preparatory work includes verifying the field wiring is correctly isolated,shielded,and grounded at a single point to prevent ground loops.Each channel’s configuration(sinking vs.sourcing)must be set via DIP switches or software,matching the field device type,before power is applied.The initial commissioning involves a point-to-point check,verifying that each field device’s state correctly toggles the corresponding LED on the DI335H​and is accurately read by the TOSMAP controller software.

Routine maintenance is predictive rather than periodic.The primary activity is monitoring the module’s health status via the TOSMAP engineering workstation,which displays diagnostic alerts.There are no user-serviceable parts inside the module.In the event of a hard failure indicated by diagnostics,the module is typically replaced as a unit.In hot-standby or triple-modular redundant(TMR)systems,this can often be done online.The replacement procedure is methodical:document the configuration,power down the rack(if not redundant),swap the module,restore power,download the configuration,and verify channel operation.It is critical to use a module with identical firmware and hardware revisions.

We provide dedicated lifecycle support for critical components like the TOSHIBA DI335H.We source these modules from assured channels,and each unit undergoes stringent acceptance testing that simulates operational loads and verifies all 32 channels for signal integrity,response time,and isolation.We offer a comprehensive warranty and are prepared to support you with configuration files,compatibility verification,and integration guidance.Our expertise ensures that your high-integrity TOSMAP system maintains its certified performance and reliability for the long term.

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