ship's main engine jacket water temperature controller set point is 80 degrees but it temperature is not rising above 70 degrees. how to solve the problem?

 

Did it ever work properly?

What's the controller's output signal driving?

Is the controller's output at 100%?

Can you put the controller into manual mode and force the output to 100%? Does the temperature then increase?

 

Is the controller's output at 100%?

Can you put the controller into manual mode and force the output to 100%? Does the temperature then increase?

I presume the engine would be producing heat and PID controller would be controlling cooling water. To increase temperature, controller output would need to decrease water flow.

 

First thing I always ask in cases of this:

A) what has been changed since the last time it worked ok?
B) what has been replaced?

Putting the controller on 100% manual output is a very good one. Try to check whether the problem is the electronics or the mechanics.

david_2 already gave the advice I would give. Here are a few extra ones if those ones don't check out:

1) can you connect a calibrator to the sensor wires to check the sensor itself?
2) check the measurement input on the PID controller by connecting a calibrator/simulator instead of the sensor
3) what kind of sensor are you using? Thermocouple (what type? K?), Pt100 RTD (very sensitive to vibrations). If the thermocouple is replaced with another type: verify if the thermocouple is of the same type (K?). If you are not sure check thermocouple with glass of 100°C boiling water with sensor connected to calibrator.
4) if there is a short circuit inside the thermocouple sensor tube you will have a misreading since the measurement point is not at the tip of the sensor.
5) is the jacked controlled with a heating element? Disconnect and check the ohm value and determine of the heating element is still ok
6) is the jacked controlled with valves: check the valves for operation (maybe valve needs cleaning)
7) is there a pipe clogged? Can you check flow of liquids?
8) are you at sea? What parts do you have at hand? PID controller (same type?) valves? sensors?

I hope you can find the problem by checking these things out.
Please let us know how things are going, maybe we can give you further advice.

 

> I presume the engine would be producing heat and PID controller would be controlling cooling water. To increase temperature, controller output would need to decrease water flow.

Good point, I didn't think hard enough. it's a cooling loop, not a heating loop (unless it's a preheater from a cold start for arctic conditions?).

So, does manual mode at 0% output increase the temperature?

 

When you replace the PID controller in a cooling loop: always remember to put the way of PID control to direct type (increase of measurement value leads to increase of controller output value).
Most PID controllers are standard configured for indirect type (for heating), so increase of measured value (temperature) results in decrease of controller output value (power to heating element)

 

First thing I always ask in cases of this:

A) what has been changed since the last time it worked ok?
B) what has been replaced?

Putting the controller on 100% manual output is a very good one. Try to check whether the problem is the electronics or the mechanics.

david_2 already gave the advice I would give. Here are a few extra ones if those ones don't check out:

1) can you connect a calibrator to the sensor wires to check the sensor itself?
2) check the measurement input on the PID controller by connecting a calibrator/simulator instead of the sensor
3) what kind of sensor are you using? Thermocouple (what type? K?), Pt100 RTD (very sensitive to vibrations). If the thermocouple is replaced with another type: verify if the thermocouple is of the same type (K?). If you are not sure check thermocouple with glass of 100°C boiling water with sensor connected to calibrator.
4) if there is a short circuit inside the thermocouple sensor tube you will have a misreading since the measurement point is not at the tip of the sensor.
5) is the jacked controlled with a heating element? Disconnect and check the ohm value and determine of the heating element is still ok
6) is the jacked controlled with valves: check the valves for operation (maybe valve needs cleaning)
7) is there a pipe clogged? Can you check flow of liquids?
8) are you at sea? What parts do you have at hand? PID controller (same type?) valves? sensors?

I hope you can find the problem by checking these things out.
Please let us know how things are going, maybe we can give you further advice.

Yes, Patrick, good list of questions.

I'd ask the same questions, but I'm jaded after 20 years of typing all those questions out, only to never get a single response from the OP. So, I now tend to limit my response to a couple quick questions to see if the OP is even engaged.

 

Yeah that is also always what I have in this forum: there is a topic starter with already a very vague name, that gives a vague description of a problem without any brand or model codes.
Then you give advice and don't hear anything back.....

At least have the courtesy as a topic starter to thank the repliers for the advice, and let them know if the problem is solved (or not).

 

Just another waste of time from someone that joins and posts on the same day to never be seen again. There are very few posts on this forum as it is, maybe Ai generated to bump up the number of posts?

 

yes, we have to change the way this forum works.

First people have to start a topic with:
1) a real sur and last name
2) direct link to the linkedin profile so we can verify you are a real & serious person working at a technical company
3) the name of the company you work for + address + website (can also be in linkedin profile)
4) exact name & number of the equipment regarding the question
5) a really detailed description of your problem. What you already tried out and found. This way we can verify your are seriously busy solving an urgent problem and need help. Not some kind of "shooting in the air" question

 

> Just another waste of time from someone that joins and posts on the same day to never be seen again. There are very few posts on this forum as it is, maybe Ai generated to bump up the number of posts?

I can state, categorically, that the site management does not generate fake threads or posts.

The hit-and-run behavior is typical of a no-cost web forum and has been since the origin of web fora. C'est la vie.

 

Hello,

@razib , did you see all comments made?
Please respond.

Bertus

 

Hello,

@razib ,
I will close the thread as there has been no reaction.
When you want to react on the thread, report this post with the request to open the thread and I will open the thread.

Bertus