<b>Moderator's Note:</b> Sorry about the all caps message. Usually I retype them to be lower case. I don't have time to retype this today. For the future, do your moderators a favor, please use initial capital letters in sentences so we don't have to retype your messages. Thank you everyone.

WE ARE USING MARK-VI CONTROL SYSTEM FOR GAS TURBINE CONTROL. WE HAVE FACE INCEIDENT OVER VOLTAGE IN 125 VDC BATTERY POWER SUPPLY. OVER VOLTAGE SENSED BY MARK-VI CONTROL SYSTEM VME- POWER PACK AND STOP THE POWER TO VME RACK AND GT GOT TRIPPED.

WE ARE SEARCHING OVER VOLTAGE PROTECTION DEVICE WHICH WILL STOP TO 125 VDC BATTERY VOLTAGE TO MARK-VI SYSTEM IN CASE OF OVER VOLTAGE 140 VDC AND SWITCH THE SYSTEM POWER SUPPLY FROM BATTERY TO DACA. AC TO DC CONVERTER TOR OPTIONAL POWER IN MARK-VI CONTROL SYSTEM. THIS WILL PROTECT THE MARK-VI CONTROL SYSTEM TO OVER VOLTAGE AND SIMULTANEOUSLY AVOID TO MARK-VI CONTROL SYSTEM STOP.

PLEASE IF YOU KNOW ANY DEVICE TO OF OVER VOLTAGE PROTECTION WHICH COMPTIBLE TO GE. MARK-VI CONTROL SYSTEM PLEASE SHARE TO US.

CONTACT DETAILS

EMAIL : [email protected]

 

I'll try and check for your Overvoltage device, but I think your first problem is to find out why your 125 is >140V.

 

Has anyone actually checking to voltage from the battery or the battery charger?

 

Yeah, ... I'm going to chime in here and agree with CuriousOne and Bob Johnston and ask why the root cause isn't being investigated and resolved?

I'm also going to add that some kind of automatic transfer switch isn't probably the best answer, either.

Finally, I'm going to add that on several occasions I have troubleshot problems with failing Mark VI processor rack power supplies--and in every occasion the problem was caused by voltage spikes from the 125 VDC supply. On one occasion, the Mark VI was controlling a large steam turbine and DACAs (AC-DC converters frequency supplied by GE for steam turbine applications) were being supplied with 220 VAC by a very dirty inverter--one with little or not filtering on the output. (The inverter was using a large station battery (110 VDC, if I recall correctly) to power the inverter, which was being used to power the DACAs which were being used to power the Mark VI. So, there was 440 VAC powering a battery charger, supplying 110 VDC to the station battery, which was then being converted to AC to supply the DACA modules which was converting the AC back to DC to supply the Mark VI processor rack power supplies....) In the end, it was decided to purchase and install some very DC-to-AC converters with very good filtering to replace the inverter. But this was after six or seven RMPKs were damaged in the process.

A couple of the other sites had failed 125 VDC battery charger output capacitors which were the cause of the problem. And one site had just replaced their original 125 VDC charger with a very inexpensive charger which just had horrible filtering on its output.

Another thing which was discovered in the first instance I spoke about was that the GE-supplied DACAs actually AMPLIFIED any input voltage spikes or dips on their output--which made them just as much a part of the problem, or even more-so, than the dirty inverter input to the DACA. DACAs provide virtually no filtering to reduce or eliminate spikes or dips on the input from getting through to the output--and, in fact, in most cases made the spike or dip worse on the output.

There is a filter (called the <CPF>) in most Mark VI panels--but their main purpose is to prevent electrical noise from the Mark VI from getting outside of the panel on to the supply(s) and causing problems with other equipment. And, their ability to limit spikes and dips or to help "ride through" spikes and dips is marginal, at best, and should not be counted on to protect the panel to any great extent from incoming power problems.

To echo the comments of the previous respondents--the root cause of the problem seems to be being overlooked. Most panels powered by 125 VDC supply AND equipped with DACAs already have the ability to quickly switch from one to the other in the event of a loss or dip. But, this problem may also be caused by problems with the input to the DACA--which, as was noted, can amplify any spikes or dips and does not have any kind of filtering of any magnitude. It would be interesting to know how it was determined the problem was the 125 VDC battery charger--and not the DACA (presuming there is a DACA connected to the Mark VI in addition to the 125 VDC supply).

There is another issue which causes great problems for many Speedtronic turbine control panels--which is that sometimes sites experiencing battery issues remove the battery from the supply circuit and connect the output of the 125 VDC battery charger directly to the Mark VI. And this is definitely not good for the turbine control panel--the battery acts as a very large filter on the output of the battery charger, and without the battery the charger output is usually very choppy (dirty). (Many times this is done during commissioning by well-intentioned, but poorly trained, commissioning field personnel, and if it doesn't cause immediate problems (which it usually does), it does definitely weaken Mark VI power supplies, in particular.)

This "work-around" could prove to be much more expensive in the long-run than purchasing a new battery charger--if that is, indeed, the source of the 125 VDC power supply spikes mentioned by the original poster. And, it completely ignores the root cause of the problem, and, may in fact make the problem worse if DACA supply problems are the real source of the voltage spikes.

Hope this helps!