XQ1475G (PMG3516C) underfrequency, undervoltage and underspeed shutdown 1

[Banji Isioye]

Good day all,

We have a Caterpillar Gas Generator XQ1475G package with a PMG3516C engine. The features includes but not limited to:
1. EMCP 4.2 local control panel/engine control interface
2. AGC-4/EMCP 4.2 Protective Relaying
3. ADEM Type Electronic Governor

The generator was purchased for a client and was set up to synchronize with another diesel generator successfully. However after you have placed the generator package on full load, it runs for several hours then shuts down on underfrequency (2436-1), undervoltage (2440-1) and underspeed (190-1). We have run it severally and each time it shuts down it generates those codes. We have checked everything in terms of settings via ET and mechanical parts. All seems fine but it keeps shutting down.From one of the graphs I logged the Real kW and all other power parameters drops and then speed, voltage,frequency fuel parameters follow. It is as if it is terminating the ignition. Please help with suggestions, what could be wrong?
I have attached the PSRPT.

 

[waross]

Throttle Actuator invalid
Low Fuel Pressure

I would look first for a fuel reduction.
Moisture in the fuel gas condensing and freezing in a pressure reducing valve may be an issue.
Take a look at your pressure reducing valve for external frost of condensation.
Feel the PRV to see if it is very cold.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[catserveng]

Well, in the last 84 hours you have 6 occurrences of the ECM not seeing the throttle actuator, so that would be a good place to start. Depending on vintage of the actuator, a loss of comms to ECM can result in the throttle actuator closing without a command, causing the engine to stall.

Do you have CAT ET?

Do you know how to setup a datalog working off a trigger?

Best course of action would be to setup a datalog with ET and see if can capture the problem, usually a good way to start in troubleshooting a problem like this.

MikeL.

 

[catserveng]

So taking a closer look at your Product Status Report, you have a number of things going on.

Low Fuel Pressure
Low Fuel Differential Pressure
Estop (14 times in 80 some hours, are you using it that much or do you have an intermittent open circuit?)
Desired Speed Undervolts, twice, no speed reference the engine wants to drop to idle.

How many times has unit tripped?

When did it start?

Anything done to unit, liked serviced, moved, or????

Have you contacted your dealer?

MikeL.

 

[Banji Isioye]

@waross and @catserveng. Thank you for your replies. Sorry, I should have mentioned that this particular package XQ1475G was procured as fairly used equipment in the Netherlands and we are now trying to commission in Nigeria for a client. As of the time we procured it, it already had approximately 10,000 run hours. During procurement, it was tested on full load in the Netherlands but while we tried commissioning here in Nigeria, it ran for random hours many times(24 hours, 17 hours, 12 hours, 8 hours) and then shuts down each time on those codes I stated (underfrequency, undervoltage, underspeed)

The codes you could help look out for are the ones after 10,000 run hours.

We have carried out necessary pre-start checks. We have carried out inspection as directed by SIS on the following codes
1. 1042-9 ITSM: Abnormal Update Rate
2. 1440-9 Throttle Actuator: Abnormal Update Rate
3. 1440-11: Throttle Actuator Invalid

We once used the graph recorder to monitor parameters related to fuel, speed, voltage, frequency, and power. I will share the graph file (with .sdf extension) after this. From the graph, I believe we have resolved the issue on the low fuel pressure because when the engine dropped load (Real, Reactive and Apparent Power) the fuel gas pressure and gas flow did not drop until the engine had gone down completely.

@waross, we will check the fuel system as you have advised.

@catserveng,confirm my details on the graph recorder answered the data logging off trigger? If not please could you explain in details how you log off trigger

I have attached the last PSRPT we generated, I will attach the graph file next.

 

[Banji Isioye]

Please find attached graphed parameters

 

[waross]

There are several valid approaches to trouble shooting. Hopefully all will eventually lead to the same conclusion.
When there has been a change of any sort in the operation of a machine, it is often well to evaluate the possible consequences of that change.
Possible changes:
Ambient temperature:
Has there been much change?
Has the generator been moved from a temperature controlled plant to an ambient temperature location?
Do the shutdowns coincide with high ambient conditions or low ambient conditions?

Fuel:
Has the supply pressure changed? (A higher supply pressure may result in lower temperatures at pressure reducing valves.)
Has the fuel quality changed? (A lower BTU content will result in more volume passing reduction valves and a lower equilibrium temperature.)
Has the moisture content changed? (A higher moisture content may result in ice bridging or freezing of the throttle actuator.)

Has the load profile changed? (Given the random nature of the shutdowns, there may be pre-existing load related issues that were no discovered during the load test.)

Mike and I have different backgrounds, different experiences and different trouble shooting approaches.
This is not a competition between Mike and myself.
This is two honest attempts to help you get your generator repaired.
If there is a apparent conflict between Mike's advice and my advice, I will happily defer to Mike.


--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[waross]

Are you running non-condensable natural gas, condensable propane or butane or a mixture?
I have seen extreme freezing when a condensable gas was passed through a pressure reducing valve intended for vapour service.
The valve stuck because of differential contraction of the components and became inoperative.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[Banji Isioye]

@waross no problem at all. We welcome all suggestions. The main goal is to find a solution like you stated. See my replies in red
Possible changes:
Ambient temperature:
Has there been much change? Yes, there have been changes in terms of weather conditions, some operating parameters due to the synchronization set up with an existing diesel generator in the facility.
Has the generator been moved from a temperature controlled plant to an ambient temperature location? We currently cannot confirm if the plant it was stationed before we procured it was a temperature controlled system plant but we will try to find out. Note that the generator was used as a rental package.
Do the shutdowns coincide with high ambient conditions or low ambient conditions? I cannot tell if the shutdowns have to deal with the ambient conditions since we have not had any active code related to temperature for some time. We had it (High Exhaust Temperature Shutdown) initially due to debris in the exhaust when it was shipped in. We cleared that.

Fuel:
Has the supply pressure changed? (A higher supply pressure may result in lower temperatures at pressure reducing valves.) We decided to change the supply pressure due to the facility load dynamics.We currently run at higher pressure compared to the pressure at load test on procurement.
Has the fuel quality changed? (A lower BTU content will result in more volume passing reduction valves and a lower equilibrium temperature.) The fuel quality was changed due to the erratic behavior we observed. We are hoping to tweak it

​

Has the moisture content changed? (A higher moisture content may result in ice bridging or freezing of the throttle actuator.) We cannot tell the moisture content of the gas used during the load test when it was procured but we have the analysis of the gas supply in the facility where it is currently stationed which was taken last year, 2020.The moisture content is 0%

Has the load profile changed? Yes, the facility load the generator is subjected to is not too steady. It shuffles most times between 50-56% of the generator's capacity however during load test at procurement a load bank was used on full load

I have attached a document showing some key parameters at FAT on procurement and the parameters during the last run. We should return to the field by the month-end to continue with troubleshooting then we will look at the fuel system as you suggested and other suggestions others have. Thank you.

 

[waross]

I think that you have ruled out obvious fuel problems. Time for me to step aside and let Mike have a word.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[catserveng]

I'm out on a jobsite right now and don't have access to ET, will be back in tomorrow and will take a closer look at your info.

From your last PSRPT, it looks like you may have an issue with the on engine CANBus network, it could a connection, a wiring problem in a harness or a component problem. There is a lot going on and it will take some time to go thru it properly.

Please verify your serial number, make sure the serial number in the software is the same as the engines (yes, it happens, especially in the used equipment world).

Confirm you are operating this as a 480V/60Hz unit. You said the equipment is in Nigeria, right? So I'd assume you're at a site powering north American sourced equipment, like a drill or production rig?

You need to verify your fuel, get an analysis done and use GERP to get the right settings for your fuel, this is a low emission engine, looks like a charge density controlled unit, so those numbers are VERY important for performance and operations, even if the unit is not in an emissions restrictive area.

The age of unit and having an EMCP4.2 doesn't seem to match, so likely the EMCP4.2 was a retrofit, not uncommon but unless done properly can cause quite a few problems, can you verify if it is a retrofit and when it was done?

On using the datalogger in CAT ET, take a look at this,

https://www.blog-teknisi.com/2021/03/using-data-log-recorder-and-viewer-on.html

to see if it gives you a better understanding.

I'll get back to you on this as soon as I can. Have you contacted local dealer? Mantrac usually has some very good technicians and field engineers in Nigeria quite a bit, at least when I was working the field for CAT. Also have you tried the CAT Forums? Al Hunt usually is on quite a bit and by far one of the most experienced CAT Gas Engine guys in the world.

MikeL.

 

[Banji Isioye]

Thanks a lot for the feedback. Sorry I have been away for a while.
The Modbus DataLink failure alarm shows up intermittently while the engine is running but it has never shut it down. I just clear the alarm and it keeps running. I do agree a thorough inspection needs to be carried out.

The serial numbers of the ECMs match what is displayed on the ET. I have not verified the serial number for the EMCP.

It is a 480/60Hz. The engine was procured as 400/50Hz but the conversion was done by Engeryst(PON) in Netherlands. From the datasheet it is designed for both 400/480V and 50/60Hz. Yes, it is an offshore site powering crude oil production unit.

Yes, we have done the fuel analysis which I shared. I will share it again. Please confirm if the timing settings affect the performance greatly? At FAT the fuel quality was around 823 btu but for the fuel gas on the current site, the engine is stable at around 1000 btu. Using the gas analysis and the datasheet by CAT, 1000 btu falls on 28 Deg timing setting on ET however it is currently on 26 Deg. How does that affect the engine performance?

EMCP 4.2 is actually what is in the datasheet, I want to believe that is what came with it. from the history reports, there are no mentions of it being changed.

We have contacted PON and we are hoping to have them come onboard if this is not resolved soon.
Thanks.

 

[catserveng]

Ok, so if PON did the conversion I'd say it was an excellent chance it was done right.

I'll be able to get in the office and look closer at your info when I get home later tonight. I did take a quick look at your datalog, with what you had looks like a "trip" or sudden shutdown, but you need some additional data points to be sure.

The XQ packages, especially those used in the rental markets really take a beating, since you seem to be having multiple comms faults (actuators, ITSM and now Modbus) you may want to take a good look at power and grounding wiring and connections.

As for your timing, the difference will likely cause the cylinder exhaust temps to be a bit hotter. Do you have an emissions analyzer? I know you are not operating in a strict regulatory area, but these engines, especially the charge density controlled units, have a very narrow operating window for everything to work just right, and getting all your settings and adjustments correct requires you to know what your NOx emissions are, and comparing them to the CO and O2 readings to make sure you have everything in line with the mapping.

I attached a training presentation we used to do for commissioning and senior field techs. You may find it helpful. With the issues you have documented in your PSRPT and comments above, I would take a hard look at the overall wiring, connections and make sure its old life, conversion and shipping a good distance across the world and dumping it on a rig hasn't rattled a bunch of stuff loose.

Also make sure the EMCP4.2 has a current flash file, the early versions of this control had a number of ghost issues that caused a lot of nuisance problems. I would assume PON would have updated the flash files but asking to verify wouldn't hurt.

MikeL.

 

[Banji Isioye]

Hello gentlemen @catserveng and @waross. Thank you for your support. I was able to resolve the issue with the generator. So I stated earlier that the generator was converted from 50Hz to 60Hz. For this generator, the speed sensing configuration has two options which you can choose via CAT ET
Option 1- The use of MPU which was the default setting all this while
Option 2- The use of CAT data link.

I decided to use option 2 to run and see, we ran the generator for 72 hours and there was no shutdown. The problem must be from the MPU or MPU wiring or MPU wrong installation or calibration. On the other hand, I am also thinking since the MPU is installed on the flywheel with a particular number of teeth. When you convert your generator from 50Hz to 60Hz, do you also change to a type of flywheel or a type of MPU? This is the answer I am trying to get now. Thanks.

 

[FreddyNurk]

Sound more like an unreliable MPU or related equipment, particularly if it runs for a few hours before shutting down. As far as I'm aware the flywheel and MPU sensor would be the same for either frequency, but whatever it's connected to obviously needs to be set for the correct frequency.

EDMS Australia

 

[Banji Isioye]

@FreddyNurk, thank you for the response. It is connected to the EMCP 4.2 customer control module which was always reading 60Hz even when we graphed it but I believe what must have been happening is that it shuts down the engine a second it loses communication with the MPU. I do agree it could be the MPU itself or wiring or the installation was not properly done.

 

[catserveng]

The MPU's and flywheel ring gear are the same for both 50Hz and 60Hz ratings, the only thing that needs to be changed in relation to speed when converting is the overspeed settings in the EMCP.

The flywheel ring gear for that engine has 183 teeth.

The engine ECM usually has two speed sensors being monitored, the speed timing sensor on the left hand camshaft gear, and a 3 pin powered speed pickup that generates a square wave output. Usually (but not always) if the flywheel speed sensor is having a problem you will get a diagnostic code for a speed sensing mismatch.

The EMCP4 has the option of installing a 2 pin passive MPU. If you look at the flywheel housing, on each side of the turbo/exhaust support are two threaded holes for the speed pickups, the unused holes are plugged. Genset engines usually have both sensors installed, but they are different sensors, the one for the ECM has three pins, the one for the EMCP4 has 2 pins. Remove and check both pickups, they should be clean and have no signs or impact or rubbing. If the 3 pin sensor has more than 10,000 hrs on it, replace it, they have caused problems in the past and the general recommendation is to replace them at top end overhaul. Normal adjustment for them is to turn the sensor in unit it touches the flywheel ring gear, and back it out 3/4 of a turn, then tighten the locknut. Make sure the threads in the sensor hole are clean, use a 5/8-18 tap to chase the threads of the sensor doesn't turn freely by hand.

Visually inspect the wiring harness leading to the speed sensors, they are exposed to hot exhaust if the manifold wraps or heat shields leak and can get brittle and damaged.

Hope that helps, MikeL.

 

[Banji Isioye]

Good day all,

The second Caterpillar gas engine PMG3516C that worked perfectly about 3 months ago. I have tried starting it since last week. It cranks, starts but stalls immediately after start-up without any error code on EMCP 4 display or the CAT ET. The stop seems to be an external stop it usually records on the AGC-4 display when you stop the engine normally but this time I am not the one initiating the stop. I have checked and inspected all settings, sensors and any thing that may be out of place. The actuator position command, the fuel metering valve, the turbocharger compressor bypass position all appear fine. Checked the threshold protection settings and observed during crank and start-up, none of the readings are near the threshold values.