PLANIFICACIÓN BASADA EN CASOS DE USO

DEVICE SUMMARY

DEVICE NAME CUSTOMER TAG DESCRIPTION

PH-3 --- RATCHET PUMP

88HR --- RATCHET MOTOR

43HR HS -300 HYDRAULIC RATCHET CONTROL

SWITCH

20HR-1 FV -326 HYDRAULIC RATCHET SELF

SEQUENCING VALVES

FH-B --- HYDRAULIC RATCHET OIL FILTER

33HR1 ZSL - 300 HYDRAULLIC RATCHET VALVE

POSITION

33CS-1 ZSL -304 STARTING CLUTCH POSITION

-ENGAGED SOFTWARE DESCRIPTION

The hydraulic ratchet system provides:

breakaway torque to the unit shaft during unit startup;

slow rotations during unit cool down in order to avoid shaft bowing due to non-uniform heat radiation from turbine casings combined with rotor weight;

slow rotations during long-term storage periods.

The sequence described is used to build ratchet pump 88HR command XS -104 (4HR) and starting clutch engage valve open command FV -326 (20HR-1) .The two ratcheting commands are generated at the same time by the same logic. The clutch engaged is detected by limit switch ZSL -304 (33CS-1) signal that cause the cranking motor to start.

Ratcheting commands permissive

Electric cranking motor stopped delayed XS -129 (52CR) Ratcheting commands cutout conditions

Lube oil pressure low voting trip logic HP zero speed detected for more than 60s.

HP shaft control speed signal loss HP shaft above crank speed

Unit start-up ratcheting sequence

During the unit starting sequence, if no cutout and all permissive conditions verified, the ratcheting begin as soon as the ready to crank is detected (L3ARC). It continues to operate until the HP shaft zero speed is detected (L14HR).

Ratcheting cycles during cooldown

During a stop sequence, the ratchet pump is started 60 seconds after the HP shaft is detected at zero speed; independently from the state of limit switch ZSL -304 (33CS-1) the pump remains running and rotating the shaft until the ZSL -304 (33CS-1)limit switch drop down delayed by 2s is detected. At this point the pump is kept stopped for 180 s, and then the cycle is repeated. Cooldown ratcheting cycles are stopped when cooldown sequence is completed

Manual ratcheting (Jogging)

If HP shaft is below cranking speed the ratcheting cycle can be started manually (jogging) by the local push-button mounted on the ratchet pump skid HS -300 (43HR) or by HMI push button. The local push button has to be closed for more then 2 s to rise the starting jogging command.

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The jogging sequence stops 2s after the drop down of limit switch (l33hrf) Alarms, trips and monitoring

If, during cooldown ratcheting, limit switch ZSL -304 (33CS-1)is not detected for 6 minutes, alarm is generated.

If ratcheting cycle is longer than 30s, alarm is generated.

If hydraulic ratchet motor overload is detected XS -106 (49HR) alarm is generated.

Hydraulic ratchet pump running is detected XS -107 (42HR) for monitoring purposes.

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3.8 WHEELSPACES

DEVICE SUMMARY

DEVICE NAME CUSTOMER TAG DESCRIPTION

TT-WS1FO-1 TE -208 A WHEEL SPACE TEMP. 1st STAGE FWD OUTER #1

TT-WS1FO-2 TE -208 B WHEEL SPACE TEMP. 1st STAGE FWD OUTER #2

TT-WS1AO-1 TE -214 A WHEEL SPACE TEMP. 1st STAGE AFT OUTER #1

TT-WS1AO-2 TE -214 B WHEEL SPACE TEMP. 1st STAGE AFT OUTER #2

TT-WS2FO-1 TE -209 A WHEEL SPACE TEMP. 2nd STAGE FWD OUTER #1

TT-WS2FO-2 TE -209 B WHEEL SPACE TEMP. 2nd STAGE FWD OUTER #2

TT-WS2AO-1 TE -213 A WHEEL SPACE TEMP. 2nd STAGE AFT OUTER #1

TT-WS2AO-2 TE -213 B WHEEL SPACE TEMP. 2nd STAGE AFT OUTER #2

SOFTWARE DESCRIPTION Alarms and Shutdown logic

There are two single element thermocouples (TC) in each measurement section to monitor the wheelspace temperatures.

If the average temperature of TCs located in one measurement section exceeds the related alarm level for more than 10s, a common software alarm L30WSA2_ALM is generated. This alarm corresponds to TAH-208, TAH-209, TAH-213, TAH-214 P&Id alarms.

If this common alarm remains active for more than 24 hours, L30WSA4_ALM software alarm signal is generated and shutdown sequence is started (L30WSA_SD software shutdown request).

If the average temperature exceeds the shutdown level for more than 10s, a common software alarm L30WSA3_ALM (corresponding to TAHH-208, TAHH-209, TAHH-213, TAHH-214 P&Id alarms) is generated and the shutdown sequence is immediately activated (L30WSA_SD).

For the first hour of operation after the end of starting sequence (L3 is true), WSKALM9 constant (21°C) is added to both alarm and shutdown levels to avoid shutdown due to a transient thermal distribution.

Instrumentation fault logic

Outputs from the two thermocouples located in a same measurement section are compared against each other. If they differ by more than WSKALM8 constant (65.5°C), the high spread software alarm

L30WSA1_ALM is generated and the maximum temperature value is considered for control functions.

A thermocouple signal is detected faulty when at least one of the following conditions are verified:

Thermocouple output is out of range (-26.5°C, 649°C);

Signal fault detected by hardware diagnostic.

If a thermocouple signal is detected faulty, its value is discarded and temperature value is given by the other thermocouple on the same section.

If two thermocouple signals on the same section are faulty for more then 10s, alarm signal L30WSAF_ALM is generated and shutdown sequence is started (L30WSA_SD).

Water Wash Permissive

All of the average wheelspace temperature values are compared against each other and the highest value is selected. This value is then compared to K69TWW constant (149°C), to provide water wash permissive signal (L69TWW).

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