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Manual Output Controls and Diagnostics

Safety systems are often provided with controls for manual trip and manual override.

HA manual trip causes the output to assume the alarm condition. For example, a normally-energized output would be de-energized.

HA manual override causes the output to remain in the normal condition. For example, a normally-energized output is held energized.

These manual controls can be implemented either in hardware, as represented below, or in software. If the software method is used, GMR autotest and fault processing operations are unaffected.

Hardware control usually consists of switch contacts applied to the output circuit, as shown below (for a normally-energized output).

+24V

Source

Genius

Block

Sink

Genius

Block

Manual

Override Source

Genius

Block

Manual Trip System Input

LOAD

Sink

Genius

Block

 

Manual

System Input

Override

 

+0 VDC

In this circuit, operation of either the trip or override switch can cause no-load faults, state faults, and autotest faults to be generated. In the GMR system, fault reporting can be modified to suppress no-load faults and state faults by wiring additional inputs that reflect the states of the manual override and manual trip input switch to the GMR system. The GMR system then takes these into account before reporting faults. Use of manual controls does not affect fault reporting for Short Circuit, Overtemperature, Overload, or Discrepancy faults. (see chapter 5, ªMonitoring Manual Output Controlsº).

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GeniustModular Redundancy Flexible Triple Modular Redundant (TMR) System

GFK-0787B

 

User's Manual ± March 1995

 

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Image 36
GE GFK-0787B user manual Manual Output Controls and Diagnostics