td 12 startup problems

16mar06

15mar06 td 12 fails to start:
18apr06 power supply fault contactor not closing.
20apr06: Solution: problem was the digital i/o board. POWER1 signal not arriving.

15mar06 td 12 fails to start:

Td 12 has had trouble starting for many months. On 15mar06 there was an example were the td's were stopped, the 3 were commanded to start and td12 failed to start. The listing below shows the state of td12, td4 for the 3 seconds at the startup:

--------------------------------------------------------------------
tiePrTm:   49880 
T4_DILs:    fd63>Psr4Flt  -PcuCtrl SafetyC  -Psr4MC  -Psr4MCR 1ppsInt
T12DILs:    fd67>         -PcuCtrl SafetyC  -Psr4MC  -Psr4MCR 1ppsInt

T4_DI1 :    11fd>MdrvOff  -PcuConn
T12DI1 :    11fd>MdrvOff  -PcuConn

T4_DI2 :       0>-PwrOnM
T12DI2 :       0>-PwrOnM

T4_DOLs:       4>-Pwr2On   -Pwr1On  -MampEna
T12DOLs:     800>-Pwr2On   -Pwr1On  -MampEna WatchDog

T4 brak24 :   0.000 
T12brak24 :   0.000 
--------------------------------------------------------------------
tiePrTm:   49881 
T4_DILs:    ffe7>-PcuCtrl SafetyC   Psr4MC            1ppsInt
T12DILs:    fd67>-PcuCtrl SafetyC  -Psr4MC  -Psr4MCR  1ppsInt

T4_DI1 :    19fd>MdrvOff  -PcuConn AlarmRly
T12DI1 :    11fd>MdrvOff  -PcuConn

T4_DI2 :       2>PwrOnM
T12DI2 :       0>-PwrOnM

T4_DOLs:     891>Pwr2On   StrbLt   -Pwr1On  Alarm    -MampEna WatchDog
T12DOLs:      11>Pwr2On   StrbLt   -Pwr1On           -MampEna

T4 brak24 :  24.460 
T12brak24 :   0.000 
--------------------------------------------------------------------
tiePrTm:   49882 
T4_DILs:    ffe7>-PcuCtrl SafetyC   Psr4MC           1ppsInt
T12DILs:    fd67>-PcuCtrl SafetyC  -Psr4MC  -Psr4MCR 1ppsInt

T4_DI1 :    19ff>-PcuConn AlarmRly
T12DI1 :    11fd>MdrvOff  -PcuConn

T4_DI2 :       2>PwrOnM
T12DI2 :       0>-PwrOnM

T4_DOLs:      91>Pwr2On   StrbLt   -Pwr1On  Alarm    -MampEna
T12DOLs:     811>Pwr2On   StrbLt   -Pwr1On  -MampEna WatchDog

T4 brak24 :  24.460 
T12brak24 :   0.000 
--------------------------------------------------------------------
16 seconds later: the emergency stop switch is thrown.
--------------------------------------------------------------------
tiePrTm:   49898
T12DILs:    fd67>         -PcuCtrl  SafetyC -Psr4MC  -Psr4MCR 1ppsInt
tiePrTm:   49899
T12DILs:    f923>Psr4Flt  -PcuCtrl -SafetyC -Psr4MC  -Psr4MCR CRmEmgSt 1ppsInt
--------------------------------------------------------------------

Problems with the sequence:

At 49880 the master contactor is open so there is no power to the power supplies. Td4 shows Psr4flt (which is correct) but td 12 does not show the fault.
At 49899 the emergency stop switch was thrown. At this point the Psr4Flt for td12 became active.

The Psr4Flt comes from a contactor in the power supply. This contact closes when power is supplied to the power supply. The contact is read using LS digital input bit2 (count from 0). The routing is: Dio1J3-4 to LSPIN03. There is an inline diode right after this that should be checked.

Debugging:

Get td12 to be in the failure state. Stop and start it until it fails
When it is failing, read the value of c1-1 and c1-4 on the power supply (probably check the psr book to make sure that the contactor is c1-1 to c1-4).. See if it has 24 volts on 1 side and it is not closed.
Check the input to the digital i/o to see if it agrees with c1-4.
Check the ac ripple on the signal.
Last time we had a problem like this, it was a grounding problem. Someone had forgotten to strap the power supply to the chassis. So check the grounds. When reading the value check whether things are floating or not.

18apr06: power supply is not closing fault contactor.

To 18apr06 td12 had troubles starting again. We checked and the power supply was not closing the fault contactor. 24 volts entered the c1-1,c1-4 contactactor but it did not exit. So either the power is bad or there is a fault in the power supply. We tried a second power supply and had the same problem.

20apr06 Problem was the digital i/o signal conditionig to close master contactor relay.

The problem turned out to be the digital i/o board that drove the POWER1 signal to the master contactor relay. The normal startup sequence is:

system is off.
little star commanded to start.
Little star drives POWER1 digital output for 300 milliseconds. This will provide 24 volts to the master contactor relay
The master contactor relay closes providing AC power to the power supply
The power supply closes it's fault contactor. This then provided power to the thru the little star contactor POWER2 to the master contactor relay.
The little star removes the POWER1 output. The master contactor relay is now being driven through the power supply fault contactor relay and then the little star POWER2 relay. Either of these opening will cause the master contactor to open.

What we saw when it failed was :

The master contactor was not closing.
When it failed we saw that the POWER1 signal never arrived. The signal conditioning board for the POWER1 was replaced and it started running.
The master contactor relay was also replaced.
The POWER1 output is independent of the master contactor relay. If it does not appear then no startup sequence will occur. The symptoms point to the digital output POWER1 as the problem (via the signal conditioning board).

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