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        T8891C

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        T8891C is a Trusted Speed Output FTA for T8442 Speed Monitor, providing fault-tolerant quad-redundant relay outputs with load feedback and force-guided contacts for safety-critical overspeed shutdown.
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        Warranty Policy
        We provide 1 year warranty for all remaining parts.
        The warranty period is one year from the date of shipment, unless otherwise stated in the parts description. We guarantee that the project will not exhibit functional defects that may occur under normal operating conditions during the warranty period.
        Return Notice
        The warranty period is one year from the date of shipment, unless otherwise stated in the parts description. We guarantee that the project will not exhibit functional defects that may occur under normal operating conditions during the warranty period.
        In the event of a defect, we will send new equipment, repair equipment or refund the purchase price based on our availability. You must contact us to obtain a return authorization and return the defective device to us within 14 days of reporting the defect.
        Shipping Mode
        Various transportation options are available in each country. Shipping methods and fees are clearly indicated on all quotations.Various transportation options are available in each country. Shipping methods and fees are clearly indicated on all quotations.
        Parts Availability
        Apter Power offers a wide range of components, products and services related to industrial automation. We also supply new products from a variety of quality manufacturers.
        How to order
        We have been working hard to update our inventory. If we have stock or parts available for new factory purchases, you can contact the order online. If we do not currently have an inventory, the displayed quantity will show "Ask". Please create an online quote or contact us by phone, fax or email to check availability.

        Technical specifications for T8891C

        • Manufacturer:
          ICS Triplex
        • Part Number:
          T8891C
        • Product Family:
          Trusted Triple Modular Redundant
        • Product Type:
          Speed Monitor
        • Output Channels:
          2 (one overspeed, one over-acceleration)
        • Contact Type:
          Volt-free (normally open + normally closed available)
        • Relay Configuration:
          Quad-redundant, fault-tolerant per channel
        • Relay Type:
          Force-guided contact safety relays
        • Field Interface Cable:
          TC-801 (Companion Slot I/O cable)
        • Mounting:
          DIN rail
        • Weight:
          0.7 kg
        • Estimated shipping dimensions:
          33.5x12.3x6.5cm
        • Tariff Code:
          8537109090
        • Country of origin:
          USA
        • Place of shipment:
          Xiamen, Fujian, China
        By purchasing this item, you agree to the Terms & Conditions, ApterPower is not an authorized distributor for listed manufacturers or tradenames and therefore the manufacturer's warranty does not apply. All our products come with ApterPower's 1-year warranty.

        More Information

        Overview Manuals Specifications Application Operating Environment Monitoring & Control

        Features:

        • Each output channel features four redundant relays arranged in a fault-tolerant configuration.
        • Uses force-guided contact safety relays that enable detection of welded or stuck output contacts.
        • Relays, fuses, and Hall Effect current sensors can all be replaced without removing the T8891C from the DIN rail, minimizing system downtime for maintenance.
        The T8891C is engineered for the highest level of output availability in safety-critical speed monitoring applications. Each of the two output channels (one for overspeed, one for over-acceleration) is implemented using a quad-redundant relay structure. This means four independent relay contacts are arranged in parallel and series configurations such that the failure of any single relay or individual contact—whether stuck open, stuck closed, or degraded—will not prevent the output channel from correctly controlling the field load. For example, if one relay contact welds closed, the other three relays in the channel can still open to de-energize the load. Similarly, if one relay fails to close, the other three can still close to energize the load.

        The T8891C incorporates force-guided contact safety relays, a critical feature for achieving high Safety Integrity Levels (SIL). Force-guided relays have a mechanical linkage between the normally open (NO) and normally closed (NC) contacts. If the NO contacts weld closed due to excessive current or contact arcing, the linkage physically prevents the NC contacts from also closing—or vice versa. This property allows the T8442 Speed Monitor to detect welded contacts by monitoring the auxiliary contact status signal that returns from the T8891C via the TC-801 cable. The system can thus diagnose a stuck relay before it leads to a dangerous failure.

        The T8891C is designed for maintainability in live industrial environments. All critical components—the force-guided relays, the fuses, and the Hall Effect current sensors—can be replaced without removing the T8891C assembly from the DIN rail. This "in situ" replacement capability is vital for safety-critical systems where downtime must be minimized. If a relay fails (e.g., due to contact welding or coil failure), a technician can simply open the front cover, extract the faulty relay using standard tools, insert a replacement relay, and close the cover—all while the T8891C remains mounted and other channels continue to operate (thanks to the quad-redundant architecture).

        The T8891C ICS TRIPLEX Speed Monitor may still be available for purchase and support from Apter Power beyond End-Of-Life (EOL) by the manufacturer (OEM).

        ICS TRIPLEX T8891C Speed Monitor Manuals, Datasheets, Drivers, Link Important Notice: Other accessories, manuals, cables, calibration data, software, etc. are not included with this equipment unless listed in the above stock item description. All prices are shown in USD.
        ICS TRIPLEX T8891C Speed Monitor Specs

        General

        • Manufacturer ICS TRIPLEX
        • Model T8891C
        • Condition New Original ready stock
        • Product Family T8310C,T8431C,T8480,T8442
        Important Notice: Other accessories, manuals, cables, calibration data, software, etc. are not included with this equipment unless listed in the above stock item description. All prices are shown in USD.
        • Receives governing commands from the safety controller and outputs highly accurate pulse control signals to Electro-Hydraulic Governors (EHG) or servo valves to regulate steam/gas admission.
        • Executes physical emergency over-speed trip outputs to drive quick-closing emergency shutdown valves (ESDVs).
        • Controls anti-surge valves and variable speed drives (VSD) for centrifugal and axial compressors in refineries, chemical plants, and LNG pipelines.
        • Maintains precise generator speed and frequency to match the power grid, executing safe islanding or decoupling sequences during electrical or mechanical faults.
        • Relative Humidity: 0% to 95% (non-condensing).
        • The Printed Circuit Board (PCB) is treated with a specialized chemical insulating layer.
        • Corrosion & Dust Resistance: Provides robust defense against salt spray on offshore drilling rigs and FPSOs, as well as corrosive industrial gases.
        • Mounts onto standard 35mm DIN rails or panels. Its ruggedized, compact design boasts excellent anti-vibration characteristics, allowing direct installation within explosion-proof field enclosures close to the rotating machinery.
        • Multi-Channel Pulse Output: Features 8 independent 24 Vdc Pulse Train Outputs (PTO) designed for high-speed counting interfaces, stepper/servo drives, or tachometer modulation equipment.
        • High-Density Digital I/O Integration: Simultaneously incorporates up to 40 channels of 24 Vdc digital safety I/O, allowing the system to gather speed-related auxiliary signals (such as valve limit switches, trip pushbuttons) or trigger local interlock alarms.
        • Leverages the 2oo3 (Two-Out-Of-Three) hardware voting architecture. Control commands from the main processors undergo voting on the FTA.
        • Single-Point Fault Tolerance: If any single control channel or internal component fails, the voting system seamlessly isolates the faulty signal. This ensures that the field output never interrupts and never misfires.
        Description
        The T8891C is a Speed Output Field Termination Assembly (SOFTA) designed for use with the Trusted T8442 TMR Speed Monitor system. It provides the output field interface for one rotating machine group, delivering both normally open and normally closed volt-free contacts. 

        The T8891C uses force-guided contact safety relays, allowing the T8442 Speed Monitor to detect welded or stuck output contacts via contact status feedback. Load current feedback is provided for each switching path on each channel. 

        Each relay, fuse, and current sensor on the T8891C can be replaced in situ, minimizing maintenance downtime. Isolated Hall Effect current sensors are connected in series with each of the two parallel contact switching paths per channel. Outputs from these sensors connect to the T8442 via the TC-801 field interface cable for diagnostic and fault detection. 

        Recommended usage for the T8891C outputs: normally open contacts should be used for safety-critical functions such as shutdown circuits, while normally closed contacts should be used for convenience functions such as indicators and buzzers.
        Alternative Names
        T889IC T8461 T8310 T8311 T8442 T8480 T8431C T8310C
        Technical notes
        The T8891C is a DIN rail-mounted output FTA for Trusted T8442 Speed Monitor. Features 2 fault-tolerant output channels with quad-redundant relays per channel. Supports both NO/NC volt-free contacts.
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        FAQS

        The following is a list of questions commonly asked by our customers. Please contact us if you have a question about our process that is not answered below.
        VIEW ALL FAQS
        What is the primary function of T8891C?
        The T8891C provides fault-tolerant relay outputs for overspeed and over-acceleration trip signals. When used with the T8442 Speed Monitor, it executes safety-critical shutdown commands for rotating machinery protection.
        How many T8891C assemblies can one T8442 Speed Monitor support?
        A single T8442 TMR Speed Monitor can interface with up to three T8891C SOFTA assemblies. Each T8891C serves one rotating machine group (overspeed + over-acceleration outputs).
        How does T8891C detect welded relay contacts?
        The T8891C uses force-guided contact safety relays. The physical properties of these relays allow the T8442 to detect welded primary contacts by monitoring the auxiliary contact status signal passed back via the TC-801 cable.
        Can T8891C components be replaced without removing the assembly?
        Yes, each relay, fuse, and current sensor on the T8891C can be replaced in situ. This means components can be changed while the assembly remains mounted on the DIN rail without disconnecting field wiring.

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