Speedtronic Mark2

It is basic that the voltage of a starter battery drops to half or even less at "breakaway" and cranking. If the battery is "half-dead", the regulated voltage for a control system powered from that battery may fall out of regulation and become too low.

1. When you write "5 volts input", do you mean "power supply input" or a particular logic input?
2. Have you checked the battery voltage before and during start attempt? What values did you get?
3. Have you checked the regulated voltage (card supply) before and during start attempt?
   

thanks for the reply, actually the two turbine are sharing one battery supply and registers 133vdc upon starting the turbine it drops to 127vdc and logic input drops to 2vdc. We decided turned off one turbine and it rise to 142vdc but upon switching on power supply the fuse fu3 20amps keeps on tripping this fuse supplies power module,

epsu and epsv cards, it seems some faulty module in the power supply. any help to secure the schematic diagram of this module IC3601A254A, epsu and epsv.

I am confused, Antonio.

Your first post wrote of "diesel engine starting", now you write about 2 turbines! It does not worry me which ( I have worked with both, but not GE), but it helps to be clear if it is the diesel or the turbine which does not start.

Do diesel and turbines have different starter batteries?? I am not happy with the battery supply you describe - it sounds like 60 cells lead acid [am I right???]- but a rise to 142V sounds wrong unless "battery equalize charge" is operator selected: just isolating one turbine from a common battery should NOT do that.

High (142V) Power supply could be reason for fuse blowing. However, battery voltage drop 133 to 127 on start should not cause 5V to 2V drop at logic level.

I asked if "logic input" meant the 5 volt supply or a particular logic signal - you did not define.

Some more questions...

1. Can you start the diesel on its own, without turbine??

If yes, does problem appear at turbine start??

Have you tried putting a 5V DC supply, e.g. tabletop computer supply, in place of the usual supply?? I assume you have an AC supply available normally.

sorry, for some confusing,

I'm working Turbine No. 3 and the battery is defective that's why we made a parallel

connection to Turbine No.2 battery supply and voltage at 133vdc

I mean starting the diesel engine with the 43 switch to crank position and switch the I sw. to start position only to start the diesel engine, the turbine will follow to start if the 43 switch is move to fire or auto position. during this time we have one battery supplying the two turbine speedtronic control panel.

Logic input is 5 volts from the logic gates which activates from the field sensors.

1. Yes, Diesel can be started without turbine in the crank position of the 43 switch. But the control circuit of diesel starting motor requires speedtronic permissive input from the field sensors for the logic gates of 72DSX-2 relay interlock to motor contactor.

Diesel and turbine have only one battery supplying both.

I did not try putting a a 5V DC supply from other source.

The supply in Speedtronics is only taken from the battery, AC supply only for the charger.

So you have logic input that must be 5V permit star. But it is dropping to 2V when it must be 5.

Is the 5V supply to all logic dropping to 2 volts, at same time the needed logic input drops to 2V ????

I asked that before really, but you did not answer clearly.

The point is that if the supply is OK, you need to look for a bad connection or device associated with the needed logic input.

If supply not OK, you need new supply unit, repair of supply or another supply to back it up or replace it.

1. Do you know output voltage(s) and current rating(s) of supply???
2. Is it just a 5V supply??
   

"any help to secure the schematic diagram of this module IC3601A254A, epsu and epsv."

The manufacturer cannot provide these?

I'm not surprised the manufacturer cannot provide those documents. Speedtronics MKII is long past it's use by date. The earliest Speedtronics system I have worked on is the MK IV. I have since used MK V & VI and haven't encountered the problem your describing. I'll look into it