8

Output Wiring for a 16-Circuit, 4-Block Group (continued)

Output Load Considerations for 16-Circuit 4-Block ªHº Pattern

Redundant Output Groups

Minimum load:

100 milliamps

Maximum load:

2.0 Amps

Maximum inrush current:

10 Amps for up to 10 milliseconds

Maximum total load for block group:

15 Amps at 35 degrees C

Output Off Leakage Current:

2.0 milliamps

For Outputs to be Autotested:

 

Minimum pickup time:

Greater than 20 milliseconds

Minimum dropout time:

Greater than 7.5 milliseconds

Caution

Check the characteristics of each output device against the list above to verify that it can be autotested and/or used in the 4-block output group. Otherwise, critical output loads could be adversely affected.

Output Autotest and Pulse Testing

If output circuits are to be autotested, the loads will be subject to pulse testing, which is an integral part of the output autotest sequence. Pulse testing verifies the ability of a block's outputs to change state with a short pulse that is not intended to affect the actual load. Pulse testing occurs whether the output is in the On state or in the Off state by executing one of two tests. These are the pulse ON±OFF±ON test and the pulse OFF±ON±OFF test. The actual pulse width and the number of times a point is tested depend greatly on its configuration, state (ON or OFF) and the type of load (or absence of load) on the point. So, output circuits that are to be autotested must be able to withstand On and Off pulse times that are discussed below. Each output device's characteristics should be checked against the list above to verify that it can be autotested and/or used in the 4-block output group. The following Pulse Test descriptions refer to Pulse Test operation of a block configured in the GMR mode only.

OFF±ON±OFF Test

The first ON pulse is for about 1.7mS. During this time, if the No Load diagnostic is enabled, the current data is checked and recorded. After this time, the test turns the point Off and the diagnostic, volts, and current data (if No Load is enabled) are checked. If the correct voltage and/or current data is NOT reported, the time constant is increased and the process repeats. If the correct voltage and/or current data is reported after any of the pulses, the test is passed and no further pulsing of the point occurs. The maximum number of pulses that can occur is 7, with a minimum duration of 1.7mS and a maximum duration of 20mS. Also, these is a delay of approximately 5 to 15 mS until the same point is pulsed again. These times depend greatly on the configurations of the other points.

ON±OFF±ON Test

Similar activity occurs for this test. The initial time a point is Off is about 5mS. The only fault checked for in this case, however, is that the volts feedback agrees with the

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GeniustModular Redundancy Flexible Triple Modular Redundant (TMR) System

GFK-0787B

 

User's Manual ± March 1995

 

Page 193
Image 193
GE GFK-0787B user manual Output Autotest and Pulse Testing, OFF±ON±OFF Test, ON±OFF±ON Test