ICS Triplex T8442 T8442C TMR Speed Monitor

The Trusted® T8442 TMR Speed Monitor monitors the shaft speed and acceleration of rotating machinery. It provides machine protection for over-speed and over-acceleration shutdown functions. Typical machinery applications include steam and gas turbines driving pumps, compressors and generators. A T8442 Speed Monitor Module within a Trusted System provides the capability to perform turbine speed control independent of the machinery protection functions.

 

 

Manufacture	ROCKWELL ICS TRIPLEX
Model	T8442
Part Number	T8442C
Description	Trusted TMR Speed Monitor
Origin	USA / Mexico
Dimension	32*30*28cm
Weight	1.25kg

 

Each T8442 has three monitoring and control groups. Each group provides the Speed Monitoring and shutdown control facilities required for one rotating machine. Up to three turbine trains can be handled by a single T8442. A single rotating machine group comprises of three separate Triple Modular Redundant (TMR) speed input channels and two separate quad redundant, fault tolerant output drive structures. Turbines having more than three speed pickups can be accommodated by combining monitoring and control groups.

 

The speed input channels are designed to interface directly with a Trusted T8846 Speed Input Field Termination Assembly (SIFTA). A single T8846 provides signal conditioning and field cable termination facilities for the nine TMR speed input channels required for three rotating machine groups. Both active and passive speed probes can be accommodated by the T8846. Active probes can be powered from the field cable termination.

 

 

• Three rotating machine groups.

• Three Triple Module Redundant (TMR) speed inputs per rotating machine group.

• Active or passive probe speed inputs.

• Two quad redundant, fault tolerant, volt-free shutdown control output structures per rotating machine group.

• 2500 V impulse withstand opto/galvanic isolation barrier.

• Galvanic isolation between field Inputs/Outputs.

• On-board Sequence of Events (SOE) reporting with 1 ms resolution. • Hot standby module configurations using companion slot.

• Hardware Implemented Fault Tolerance (HIFT).

• Front panel status LEDs indicate module health, operating mode and rotating machine group Input/Output status. Comprehensive automatic diagnostics and self-test.

• TϋV Certified IEC 61508 SIL 3.

 

Speed Output Signals：

Speed output signals are from normally energized relays with both normally open (de-energize to trip) and normally closed (energize to trip) volt-free contacts available. Hardware fault tolerance is maintained through the use of a quad relay structure with shared paths.

Each group provides an output signal for over-speed and also for over-acceleration.

 

Speed Input Signals：

The speed inputs are arranged as three groups of three inputs. Each external speed sensor input on the Module is monitored by three separate Speed Monitoring circuits.

Hardware fault tolerance is provided for each sensor input on the Module

 

Communications：

The only external communication interface available to the T8442 Speed Monitor is the Trusted System IMB.

The Trusted System architecture allows many intermediate transport methodologies between the IMB on an I/O Chassis and the IMB on the Main Controller Chassis.

 

1.Fault Reporting

   Input Module faults are reported to the user through visual indicators (LEDs) on the Front Panel of the Module. Faults are also reported via status variables which may be automatically monitored in the application programs, and external system communications interfaces. There are generally two types of faults that must be remedied by the user; external wiring and Module faults. External wiring faults require corrective action in the field to repair the fault condition. Module faults require replacement of the Input Module.

    The Module monitors the speed input to determine if they are within the appropriate parameters.

2.Field Faults

    The input circuits of the Module may be used to detect field wiring faults in addition to alarm states. To achieve this, line monitoring components must be fitted to the field device.

    By comparing the input signal from the field with pre-configured alarm thresholds, the Module can automatically detect field wiring faults. When a field signal fails open or short-circuit, or to an intermediate value, the input channel status LED will flash red (default setting). The corresponding input state will be reported and the line fault status for that channel will be set to '1'. All other input channels will be unaffected, except in the case of common cause wiring faults in the field.

3.Module Faults

    Extensive diagnostics provide the automatic detection of Module faults. The TMR architecture of the Input Module and the diagnostics performed verify the validity of all critical circuits. Using the TMR architecture provides a fault tolerant method to withstand the first fault occurrence on the Module and continue normal input measurements without interruption in the system or process. Faults are reported to the user through the Healthy status LEDs on the Front Panel of the Module and through the INFO and HKEEPING variables. Under normal operations all three Healthy LEDs are green. When a fault occurs, one of the Healthy LEDs will flash red. It is recommended that this condition is investigated, and if the fault is within the Module, it should be replaced.

    Module replacement activities depend on the type of spare module configuration chosen when the system was configured and installed. The Module may be configured with a dedicated Companion Slot for a spare replacement Module. SmartSlot operation is not available. Refer to Operator and Maintenance Manual for Module replacement procedure.