ICS Trusted Speed Output Field Termination Assembly T8891
Description:
T8891 is ICS Trusted Output field termination assembly for use with the T8442 TMR Speed Monitor. The Trusted® Speed Monitor Output Field Termination Assembly (SOFTA) is a DIN rail mounted piece of equipment. It provides the output field interface for one rotating machine group when used as part of a Trusted T8442 Triple Modular Redundant (TMR) Speed Monitor system.
Both normally open and normally closed volt free contacts are available on the field terminals. This allows using the SOFTA in energized to trip and de-energized to trip configurations.
The two relay output channels are arranged as quad redundant, fault tolerant structures. Failure of any one relay or contact will not affect the load, or the ability to control the load.
Load current feedback to the T8442 Speed Monitor is provided for each switching path on each channel.
Force guided contact safety relays are used. These allow the T8442 Speed Monitor to detect welded or stuck output contacts via the contact status and load current feedback from the SOFTA.
Each relay, fuse and current-sensor can be replaced in situ.
Features:
• Two online tested, fault tolerant, volt free contact output channels.
• Each output can be used as either a normally open or a normally closed contact.
• Fault tolerant quad redundant output relay structure.
• Load feedback monitoring.
• Contact status feedback.
• Force guided contact, safety relays.
• Standard DIN Rail mounting.
• Each output rated.
• Relays, fuses and current sensors can all be replaced in situ.
A single Trusted T8442 TMR Speed Monitor interfaces with three T8891 SOFTA assemblies.
A single SOFTA assembly provides the relay switching elements for one over-speed output and one over-acceleration output.
For each output channel, an isolated Hall Effect current sensor is connected in series with each of the two parallel contact switching paths. The outputs from these sensors connect to the T8442 via the TC801 field interface cable and are used for relay contact diagnostic and fault detection purposes.
Force guided contact, safety relays are used on the SOFTA assembly. The physical properties of these relays verify that welded primary contacts can be detected by monitoring the auxiliary contact status signal. The contact status signal is passed back to the T8442 via the TC801 field interface cable for diagnostic and fault detection purposes.
The output contact can be used as a normally-open (de-energized relay) or a normally-closed (de-energized relay) contact for connection to the field load. They are electrically isolated from all other signals on the T8891 SOFTA and T8442 Speed Monitor.