CSA

I am grateful to your response.
Thank you sincerely.

Best regards!
Neo

 

Neo,

Whoa! What about L14HT at your site?!?!?!

How is L14HT used at your site?

What are the values of TNK14HT1 and TNK14HT2?

 

CSA:


TNK14HT1 = 8.4
TNK14HT2 = 3.2

1)<pre>
L14HT L14H_ZSPD_BP
------|/|-------------( )</pre>
L14H_ZSPD_BP = Zero speed trip bypass logic
L14HT = Cooldown slow roll start speed relay

2)<pre>
L14HT L14H_ZSPD L4 L12H_FLT
------||---------||----------||-------( )</pre>

3)<pre>
L4ETR1_FB L4 L14HT L3MP_ALM
-------|/|------------||-----||--------(T)
| 1.5SEC
L4ETR2_FB |
-------|/|-----
|
L4ETR4_FB |
-------|/|-----</pre>
L3MP_ALM = MASTER PROTECTIVE START CHECK ETR FAULT
L4ETR1_FB = Emergency trip #1 relay(???)

4)<pre>
L4 L14HT L28FD L83SUFI L30D_CRN
-----||---------||-------|/|--------|/|-------( )</pre>
L30D_CRN = Normal display message CRANKING

5)<pre>
L14HT L45FTX L4VGRUN
-------||------|/|--------( )
| l4vgz1
| /|-----( )</pre>
6)<pre>
l3RS L1S L4 L1XX L5EX L3SFLT L1X
---||------||-------||--------||------|/|----|/|------( )
L14HT | | L4Y |
---||---- |----||-----
L1X |
-------||-------</pre>
CSA, that is the all the places where L14HT is used.

Best regards!
Neo

 

Neo,

I believe L14HT will be a logic "1" when the shaft speed is above 8.4% speed (5100 * 0.084 = 428 RPM), and it will be a logic "0" when the shaft speed is below 3.2% speed (5100 * 0.032 = 163 RPM). [These numbers are approximate since I don't know what the Load Gear Box rating is, but this is close enough.]

Let's analyze the usages of L14HT.

1)<pre>
L14HT L14H_ZSPD_BP
------|/|-------------( )</pre>
L14H_ZSPD_BP = Zero speed trip bypass logic
L14HT = Cooldown slow roll start speed relay

I know what this signal was used for in the Mark V, but I'm not sure in Mark VIe. Where is L14H_ZSPD_BP used in the application at your site, Neo?

But, still, this logic says that once the shaft speed is above 8.4% during starting/acceleration the "Zero speed trip bypass logic" will be a logic "0", and it won't go back to logic "1" until the shaft speed drops below 3.2% speed. Hmmm....

2)<pre> L14HT L14H_ZSPD L4 L12H_FLT
------||---------||----------||-------( )</pre>
This rung says the protective speed fault is only active when L4 is a logic "1" and the shaft speed is above 8.4% speed. When only enable the protective speed fault when the shaft speed is above 8.4% speed? Why not enable it when L14HR is a logic "0" OR when L14HRZ is a logic "1." Why wait until the shaft speed is above 8.4%?

3)<pre> L4ETR1_FB L4 L14HT L3MP_ALM
-------|/|------------||-----||--------(T)
| 1.5 SEC
L4ETR2_FB |
-------|/|-----
|
L4ETR4_FB |
-------|/|-----</pre>
L3MP_ALM = MASTER PROTECTIVE START CHECK ETR FAULT
L4ETR1_FB = Emergency trip #1 relay(???)

Again, why wait to enable this alarm (checking to see if the ETRs of the TREG are not picked) up until the shaft speed is above 8.2% speed? The ETRs should be picked up when L4 picks up, so .?.?.? Maybe when L14HR is a logic "0" OR when L14HRZ is a logic "1", but .?.?.?

4)<pre> L4 L14HT L28FD L83SUFI L30D_CRN
-----||---------||-------|/|--------|/|--------( )</pre>
L30D_CRN = Normal display message CRANKING

Again, why wait to enable the CRANKING message until the shaft speed gets abouve 8.4% speed.?.?.?

5)<pre> L14HT L45FTX L4VGRUN
-------||------|/|--------( )
| l4vgz1
|/|-----( )</pre>
This rung just starts the Load Compartment vent fan, but that's usually done when flame is detected, so why start the fan anytime the shaft speed gets above 8.4% speed?

6)<pre> L3RS L1S L4 L1XX L5EX L3SFLT L1X
---||------||-------||--------||------|/|----||-------( )
L14HT | | L4Y |
---||---- |----||-----
L1X |
-------||-------</pre>

This is the one that really bothers me--a lot. Here, during a coastdown from either a trip OR and normal fired shutdown L4Y will be a logic "1" 1 second after L4 drops out. Because L14HT is a logic "1" in parallel with L3RS, if L1XX is a logic "1" then L1X will go to a logic "1" and latch in! I believe the only thing that will prevent L1XX--and L1X--from going to a logic "1" would be L94X, which I believe drops out when L4 drops out. It would be great to see where else L1X is used in application code. And, it would be helpful to know when L94X drops out.

L14HT is for machines with a cooldown method <b><i>other</i></b> than a hydraulic ratchet. I could understand using something like L14HT for a few of the other rungs above, but not for a couple of them. I think it could lead to some unusual and intermittent operation under some circumstances.

So, it could be useful to look at where L1X is used, and when L94X drops outs (to pick-up L1XX, and allowing L1X to pick up when L4Y picks up--and latch in).

 

Neo,

Do you want to take this any further--the L14HT analysis? I got the impression, from this thread, that there may have been an issue with 88CR and starting that was being investigated, and I wonder if if's because of the L14HT contact in the L1X rung. I really don't think it belongs there. L14HT in parallel with L3RS says it's not necessary to have a 'Ready to Start' to initiate a START if L14HT is a logic "1". Seems very odd this one.

Very odd.

Again, 14HT isn't normally used for machines with hydraulic ratchet; only for machines with slowroll or turning gear (continuous slow spinning of the shaft during cooldown).

Anyway, let us know if you want to continue this thread, and if you want to get back to the L4 journey.

 

CSA:

My answer is always YES!

Should i open other thread to continue L4 journey? And where should i start?

And i am a little confused about L14HT in L1X rung too. And i happened to see L1X rung at anther site that is a little different from the previous one.

Best regards!
Neo

 

Neo,

I would say, yes; open another thread for L4.

As for the L14HT in L1X. What did the L1X rung look like from the other site? And what kind of turbine was that L1X rung being used for (another Frame 6B)?

I think it might be acceptable to use a NO L14HR in place of the NO L14HT in L1X (in parallel with L3RS), but I'm pretty certain that L14HT, configured as you described (with the TNK14HTn values you listed) is incorrect for a Frame 6B with a ratchet. You should get GE's assistance with this, though, and I would like to know what they say about this.

So, let's get after finishing our L4 journey. We have other things to discuss (TREG and TRPG, specifically). And, whatever else you decide to ask about--in separate threads, of course.