FT8 – FT8 & Solar – Turbine Technical Information

ART246 – FT8 – How to locate “Tunables Tags” in Control Assistant

Donald Murphy — Wed, 04 Sep 2024 22:30:15 +0000

Article Reference – ART246

FT8 instruments don’t have “Zero” and “Span” calibration adjustments, therefore the adjustment is done in the control software called “GAP”. This article is going to describe how to locate the adjustment addresses called “TUNABLES”, so that you can calibrate the control signal.

The FT8 Electrical Schematic Drawings and GAP Logic, have all the inputs and output channels in the order you find them on the RACK – CARD – CHANNEL, starting with Rack 1, Card 1, Channel 1, and continues to the last Channel, in the last Card, in the last Rack.

There isn’t an index of instruments, as you normally find on schematic drawings, to indicate the drawing page number where the instrument is located. Therefore you need to start with the “Input / Output List”. This is a drawing (list of all the inputs and outputs that enter the control system) which can be found in the “Project Documents”. The following information is what to expect in the I/O List. This is a “Mobile Pac” (yours may be different).

I am going to use Pressure Transmitter PT628 as an example in this article. You can see it is located in Rack 1, Card 6, Channel 4.

Once Control Assistant is open, you need to click on the “Two Eye” icon indicated by the curser.

If a connection was previously established with the CPU, you can accept the default values and select “Connect”. If this is the first connection you need to set up the communications with the correct protocol. This will not be discussed here.

The graphic below shows Control Assistant trying to establish communications using “OPC Servlink Server” (which is like a software driver) trying to make the connection to the CPU. It is trying to connect to “Port” IP Address 172.17.1.1. The Control ID which is VXM00020665 is the CPU identification tag. This ensures you are connecting to the correct CPU (as there may be more than one turbine on the network).

What you should now see, the processor name – in this example VXM00020665.

Clicking on the + will show the complete list of categories.

Remember where the transmitter PT628 was located in the “Rack – Card – Channel” ………. (1-6-4).

So go down until you find the Category A1_A06_AIO. This corresponds to the card which contains PT628.

Double click on the “+” at A1_A06_AIO and there are a lot of entries under this. These are called Blocks. There will be many blocks including a block for every instrument that enters or exits this card 1-6-4.

Down towards the bottom of the list you will find PT628.

Now double click on “+” to see a list of all the inputs and outputs to this block.

Now drag the two tunables and the output value in PSIA, to the right hand side of the screen as shown below. You will see the effect of any changes in the Output Value while tuning the Gain and Offset.

When you attempt to change any of the tunables you will be asked for the password, it is “1112”.

Once the change has been made using the up and down arrows (green arrow), you will have to save the changes to the control (non volatile memory). You can do this by clicking on the yellow arrow pointing down at the chip.

Another way to save the changes is to select the processor name and then right click and select Save Values. Should someone reboot the CPU the changes you made will be loaded.

You should also save a copy of the Tunables on the hard drive of the display. To do this click on the icon indicated by the yellow arrow and you will download the Tunable File to save where you wish.

This method of selecting tags can also be used in Control Assistant “TREND VIEW” to collect live data of “ANY GAP TAG” – not only analog values ……… Very powerful for troubleshooting.

END OF ARTICLE

ART245 – FT8 Battery charger ground faults

Donald Murphy — Wed, 26 Jun 2024 19:13:06 +0000

ARTICLE REF – ART245

This is the front panel of a Hindle Power AT30 battery charger, used for 24 and 125 VDC batteries. It is common to have a positive or negative ground alarm, indicating that some wiring is touching ground in one of the distribution circuits.

These can be tricky to find, especially if it is intermittant and not hard on ground all the time. Here is a tip that might help you quickly find the issue.

DCD2 is the 24 volt power distribution breakers. Both positive and negative pass through each breaker. If you open each breaker, one at a time, while monitoring the alarm light, the light will go out when you open the breaker with the issue. Note this is the 24 volt distribution, but the 125 volt is similar.

Another way of checking to see if there is a wire grounding is to check between and 24 volt DC wire and ground. Place the positive lead of a voltmeter on the 24 volts DC and the black lead on ground. If all is well you should read +12 volts DC. The same is true of the negative wire, but it will read -12 volts DC.

This happens when there are capacitors connecting positive or negative wires to ground, in the control system. On the FT8 there are many. This is often done to eleminate signal spikes which can cause shutdown false signals.

If you have an issue with a positive wire touching ground there will not be an even split +12 / -12 volts DC. It may go +4 / – 20 volts, it depends on the contact and resistence with ground.

FT8 Training – Turbine Cooling Air (TCA)

Donald Murphy — Mon, 24 Jun 2024 19:50:00 +0000

Subtitles coming soon.

ART217 – FT8 – Sixth stage bleed valve training video

Donald Murphy — Thu, 20 Jun 2024 12:55:54 +0000

ARTICLE REF – ART217

This is a training video on the Sixth Stage Bleed Valves on the FT8. This gives a detailed description of operation and control of these valves.

ART240 – FT8 Bently Nevada 3500 Alarm Testing (complete)

Donald Murphy — Wed, 19 Jun 2024 19:37:03 +0000

ART REF – ART240

This training video is the complete check of all the channels of the BN 3500 as applicable to the FT8. This includes the Velocity transducer channels A, K, S, Water Injection & Collector Box Alignment.

Subtitles in English.

ART239 – FT8 Flyback Diodes

Donald Murphy — Wed, 19 Jun 2024 19:35:47 +0000

ARTICLE REF – ART239

This video is going to discuss the use of Flyback Diodes, why they are important, and how to test them. Note that these are used on Solar Turbines as well as Pratt & Whitney FT8.

Subtitles available in English – Spanish – Turkish.

ART238 – FT8 Communicate with DVP driver

Donald Murphy — Wed, 19 Jun 2024 19:34:20 +0000

ARTICLE REF – ART238

The DVP driver was introduced to the FT8 mainly due to issues the old Em driver which was having with the Gas Valve. When a unit shut down, the power was not automatically removed from the driver. The driver constantly sends signals to the gas fuel valve to correct very small differences between the commanded and actual valve position. The gas fuel valve uses a epicyclic type of reduction gearing inside the valve, which allows for very precise positioning. This constant movement of the gearing causes the gears to wear out and the valve to fail.

The software may take several minutes to execute. Be patient and give it time.

You should see COM7 as a connection option.

Select “Connect”

This is the opening page.

ART076 – FT8 – Controls Training – Startup data.

Donald Murphy — Wed, 19 Jun 2024 13:40:00 +0000

ARTICLE REF – ART076

Have you ever wished to be able to have every analog value recorded during a start-up. That is what this is issue is all about. +250 signals collected every second during a twinpak start-up. Serious stuff.!!!!!!!!!!!!

Excellent for troubleshooting.

Excel spreadsheet with all the data has been sent to all who have registered their email with me.

ART075 – FT8 – Lube oil logic & alarms

Donald Murphy — Wed, 19 Jun 2024 12:40:01 +0000

ARTICLE REF – ART075

These slides are from a presentation I give for FT8 Controls Training.

ART074 – FT8 – GAP Logic blocks

Donald Murphy — Wed, 19 Jun 2024 12:39:02 +0000

ARTICLE REF – ART074