Carrier CCN

[wormy]

Posted this in the wrong part of the forum. (and got no replies... hehe)
Maybe if I post it here.... you guys can help.
I may have already answered my own question (least part of it...)
but since I got this far..... here it goes...

20 Ton RTU with PremierLink on Courtroom.(networked with Carrier Comfort Network)
Humidity is way out of control.
Its a two stage unit, but CCN is not letting the first stage run for very long.
The cooling algorithm stages the compressors. Looks like its getting max
temp control, but losing humidity control.

With an empty courtroom, 70 degree return (78% RH ).
82 ODT
Compressors turn off after satisfying setpoint
Room warmed back up.
1st stage compressor came on
Ran for... oh... 3-5 minutes
2nd stage compressor came on
Both stages run till stat was satisfied
Both compressors turn off together

Small amount of outside air. Equipped with motorized outside air damper
not connected to CCN.

These are the only settings I could find that might have
any bearing on the situation....


COOLING PID — The PremierLink controller reads the
space temperature sensor and compares the temperature to
the current high set point. If it exceeds the set point, and
cooling is configured and available, the controller then calculates
the required supply air temperature to satisfy the given
conditions.
The Cooling PID includes the following set points: Proportional
Gain, Integral Gain, Derivative Gain, and Starting Value.
Proportional Gain: Range 0.0 to 40.0
Default Value 6.0
Integral Gain: Range 0.0 to 10.0
Default Value 3.0
Derivative Gain: Range 0.0 to 20.0
Default Value 5.0
Starting Value: Units degrees F (degress C)
Range 40.0 to 90.0
Default Value 70.0


I have no idea what Proportional gain, Integral Gain, etc means.
Carrier was nice enough to keep me guessing.


Here's a link to the install manual


I have another system on an open office area doing the same thing.
68 Degree's /w 65% RH
It has an older version of the Premierlink
Here's the book on that one


Have to add to the original post from here....
After posting this, we had another system go down at the Justice Center.
Repaired wire connections to contactors.
While I was there, I set up my digital sling psychrometers in the rooms
I had high humidity in to see how well my prior adjustments went.
The maintenance guy that was over the building had adjusted the sheave on the pulley everytime his belt was loose.... guess it was faster for him that way LOL.
Had the CFM way high resulting in poor humidity control.
I got that system back down to around 340 CFM / ton
That system also had both compressors low of refrigerant.
I now have 68 room temp and 53% RH... much better.
68 room temp was warm to them at the higher humidity level.... now
they are freezing.... WOOT
Attached to that system through the System Pilot and found the stat was reporting 73 degrees. So I adjusted the Space Temp Trim -5 degrees in the Service Configuration Table.
Seems like every Carrier zone system I ever dealt with (Carrier Comfort Zone... I know this is probably way down on your totem pole hehe)
I've had to calibrate every sensor.
I wasn't expecting to do that with such a nice system.
Guess I shouldn't Assume anything.
I don't have much experience with the CCN system...
we've installed two systems with it (post offices)
and I've got a few chillers with it built in.

Wish I could learn more about them.
I'd love to do controls. Went to college to program robotics.
dropped out though... was working in HVAC and fell in love with it.
everytime I worked in a factory, I couldn't wait to get out.
I couldn't imagine myself working in the same building on robots for years
to come. Loved to go to different places everyday.

I've gotten so sidetracked, I've forgoten what the heck I was posting this for.
Guess I was mainly just typin to be typin..... oh well.

If anyone read this far...
Maybe you could just let me know what those settings mean.
Here they are again...
COOLING PID — The PremierLink controller reads the
space temperature sensor and compares the temperature to
the current high set point. If it exceeds the set point, and
cooling is configured and available, the controller then calculates
the required supply air temperature to satisfy the given
conditions.
The Cooling PID includes the following set points: Proportional
Gain, Integral Gain, Derivative Gain, and Starting Value.
Proportional Gain: Range 0.0 to 40.0
Default Value 6.0
Integral Gain: Range 0.0 to 10.0
Default Value 3.0
Derivative Gain: Range 0.0 to 20.0
Default Value 5.0
Starting Value: Units degrees F (degress C)
Range 40.0 to 90.0
Default Value 70.0

[AutoPilot]

PID is complicated.. Does the system have any trending? you're going to want to know how it's operating both before and after you mess with PID loop.

[wormy]

Did a search through the installers manual....
didn't see anything about trending.

I feel like such a newb.
I want to learn more about the stuff, but lack the resources.
I'm not sure how I could find out. :/

The system is relatively simple.
System Pilot.
Two different style space temp sensors (T55 and T56 I think)
and a Premierlink controller attached to each unit
All the Premierlink Controllers have a Supply Air Temperature Sensor
25 or 26 Gas Packs. Ranging from 3 ton to 20 ton.
Some units have economizers, some have motorized outside air dampers,
but neither one are connected to the CCN.

I need to confirm that an outdoor temp sensor is attached and check
the calibration.
Also need to be sure that temp is being broadcast across the network
so that the units can stage correctly.

The building used to have an old Carrier Networked control system
Not sure what it was called.
I remember working on it and reseting the zone sensors.
Prisoners would snap the front off... rotate a dial labeled A-F or something
and start changing settings till it would no longer function.
Then call me in to set it back up to run.

Anyways.... the maintenance man convinced them
they needed to upgrade to the latest greatest thing
and they did it.
Of course... they need not worry about having an experienced controls person
to install it....
They had a prisoner that knew how to service units.
"Heck... he already replaced every heat exchanger on the roof... not to mention half the compressors. If he can do that, well shoot... he can do anything"
I got in on the project the day the 'prisoner' was to be released hehe.
Since he was fixing to leave... they had to get someone down there
for him to go over what he did. Nobody there knew how to work it.
The maintenance man was under suspension for taking the 'prisoner' to
another county to work on a cooler at a Los Portales.
TBI was there investigating that while I was there hehe.


Problems so far.

High humidity (at least two systems so far, maybe more)

While attached to some of the premierlinks, the ODT reading has CTRL beside it. Gotta figure out what that means.
Others have * -40 which (if I'm right) means its not set up to recieve the ODT from the CCN and since it don't have one directly attached to those particular Premierlink Controllers, then it shows the asterisk and -40.

Can't communicate with one premierlink properly.
I 'attached' to it
started checking settings
then the display on the System Pilot showed a dark block (where the asterisk shows up as described in the other problem before this one) for each setting
think it flashed 'Failure to Communicate' at the bottom
I'm wondering if the 3 conductor communication cable is longer than 1000 Ft
and needs a Repeater.
Going to take something to measure it off with the next time I go.
I haven't a clue how the com cable is running. I'm going to have to guess.
I don't have a Service Tool to check out the individual Premierlink.
If worse comes to worse, I'll have to trade one from another unit thats working and see if that premierlink will attach and function correctly.
I got a bad feeling the com wire is
Loose, has a Broken conductor, or is shorted to the sheathing
(duct rated wire that runs through return duct. Not sure were it comes out.)
And the unit serves the jail area.


There are sections of this forum where folks get riled up about DIY'ers
I'm hoping you control guys don't get too riled up over a Residential/Commercial tech coming over to the control's side

[wormy]

Crap.... I'm having one of those days....
I got completely sidetracked....

I'll keep this short and simple.

PID Loop
Not planning on touching that till I get the sensors
calibrated and units running correctly. (the units have been hacked to death by the maintenance man. Least the 'prisoner' got a lot of it straightened out while he was there, though he went as far as he could with what tools he had)
I'm mainly just curious what the settings do for the sake of
knowledge.

[gbfromsd]

I cant scientifically explain exactly how PID works, however it is a mathematical formula by which the controller figures out what response it outputs based on a change to the input. Proportion - think of it as how far off setpoint it is since it last looked. Integral - think of it as how often it takes a look. Derivative - overdrive button for just in case.
Controller looks at the input and goes P*delta + I*delta +D = response (or something similar).
It's likely your PID calc is allowing 2nd stage to come on early and hang on late causing shorter cycling. If the algorithm says turn stage 2 on with a calculated demand above 50% then for a 1 or 2 degree deviation under normal occupancy you'd want it to hang on 1 compressor unless it continues to climb so you need to back off on it's calculation.
Larger P value - less sensitive
Smaller I value - less sensitive
D value - ? Not unless you need it.
Its a trial and error and should be charted. This adjustment could take days.

[wormy]

Performed a search for Integral Gain
and found links to a wealth of info concerning PID.

Thought it was just a Carrier thing.... looks like I was wrong.

[Balibe]

I have no idea what Proportional gain, Integral Gain, etc means.
Carrier was nice enough to keep me guessing.

A PLink is mainly designed for RTU's. The default settings for the PID Loops should work fine. I have never had an instance to adjust these in a Plink, not saying you may not need to.

The PLink has the capabilities to do dehumidification control, if your application needs it. You need to add a sensor & setup PLink. [Note: You can’t do both humidity & IAQ control with a PLink, must be one or the other].

Before adjusting anything in the PLink, I would take a look at the overall picture. There could be another reason for your humidity issues. You mentioned a courtroom, with the courtroom empty you could probably have too much OA [sized to max people] and too little load in the space with no people. This will cause the space to cool down fast as the unit is sized for max load and cycle off before removing the humidity. With a space designed for a lot of people, even 50% [one compressor] can be too much. A/C is designed to gradually cool the space and remove the humidity in the process.

The PID loop is a common and not specific to Carrier. Most control algorithms use this type of control, which has been around since the start of DDC controls. Below are the equations for the PID Loop for Carrier to help you understand. If you decide to modify the PID Loop, you can watch the operation of the algorithm in the maintenance table.

Error Calculations:
Error1 = Setpoint – Value of Controlling Sensor
Error2 = Submaster Reference – Value of Submaster Sensor

Term Calculations:
P Term = (Error1 * Proportional Gain)
I Term = (Error1 * Integral gain) + Previous I Term
D Term = (Current Error1 – Previous Error1) * Derivative Gain

Single Loop Algorithm Equation:
Output = P Term + I Term + D Term + Starting Value

Dual Loop Algorithm Equations:
Master Loop:
Submaster Reference = P Term + I Term + D Term + Starting Value

Submaster Loop:
Output = (Error2 * Submaster Proportional Gain) + Center Value[/I]

Hope this helps ……

[colddr469]

The way it was described to me was in an analogy, here goes:
Picture a man driving a car a standard ems is the cruise control all is fine on a straight road with no deviations but when there is a hill the deviation from set point is a reactive response not a proactive one. When a man is driving he sees the hill in advance and applies more pressure on the accelerator to maintain his speed or set point (this is proportional gain) as he reaches the crest of the hill he knows that he needs less pressure on the accelerator so he backs off in an attempt to not go over his speed or over shoot the set point (this is Integral gain) The derivative the time that output is changed from set point either under or over and is used to help quicken the response and get back to set point ( its kind of like the brakes as it helps keep the Proportional & Integral on track.
Its the best I can remember but for the most part Proportional and integral are the 2 points you could tweak in very small measures with large amounts of time to observe the results to much adjustment will be more trouble than its worth if you could plot it on a graph it should look like an EKG for one cycle getting smaller as time goes on and the flat line would be your set point.
Hope this helps

[colddr469]

With out the software it gets alot harder to get the bugs out plus you can keep a copy after the on site people adjust in new problems load on to a laptop but you'll need a serial port ( kind of a drying breed on the new ones I think Dell is on of the only one that have serial ports any more.

[T1371]

PID stands for Proportional, Integral, Derivative. Controllers are designed to eliminate the need for continuous operator attention. Cruise control in a car and a house thermostat are common examples of how controllers are used to automatically adjust some variable to hold the measurement (or process variable) at the set-point. The set-point is where you would like the measurement to be. Error is defined as the difference between set-point and measurement.

(error) = (set-point) - (measurement) The variable being adjusted is called the manipulated variable which usually is equal to the output of the controller. The output of PID controllers will change in response to a change in measurement or set-point. Manufacturers of PID controllers use different names to identify the three modes. These equations show the relationships:

P Proportional Band = 100/gain
I Integral = 1/reset (units of time)
D Derivative = rate = pre-act (units of time)

Depending on the manufacturer, integral or reset action is set in either time/repeat or repeat/time. One is just the reciprocal of the other. Note that manufacturers are not consistent and often use reset in units of time/repeat or integral in units of repeats/time. Derivative and rate are the same.

Choosing the proper values for P, I, and D is called "PID Tuning".

Proportional Band
With proportional band, the controller output is proportional to the error or a change in measurement (depending on the controller).

(controller output) = (error)*100/(proportional band)
With a proportional controller offset (deviation from set-point) is present. Increasing the controller gain will make the loop go unstable. Integral action was included in controllers to eliminate this offset.

Integral
With integral action, the controller output is proportional to the amount of time the error is present. Integral action eliminates offset.

CONTROLLER OUTPUT = (1/INTEGRAL) (Integral of) e(t) d(t)

Derivative
With derivative action, the controller output is proportional to the rate of change of the measurement or error. The controller output is calculated by the rate of change of the measurement with time.

dm
CONTROLLER OUTPUT = DERIVATIVE ----
dt

Where m is the measurement at time t.

Some manufacturers use the term rate or pre-act instead of derivative. Derivative, rate, and pre-act are the same thing.

DERIVATIVE = RATE = PRE ACT
Derivative action can compensate for a changing measurement. Thus derivative takes action to inhibit more rapid changes of the measurement than proportional action. When a load or set-point change occurs, the derivative action causes the controller gain to move the "wrong" way when the measurement gets near the set-point. Derivative is often used to avoid overshoot.

Think of it as Stated earier, the cruise control for your car. You are going 70mph on a flat road. You begin to encounter a upward slope which is more than likely going to slow your car down. As you car begins to slow down below your set speed (SETPOINT) it will begin to add more throttle to acheive your desired speed. You reach your speed and the road begins to slop downward. To prevent overshooting it will throttle back and may apply some brake to prevent overshooting your desired speed... Hope this helps some...

[wormy]

Preciate everyone's input on this.
Gotta take some time and let this stuff sink in.
Although, now it looks like I'll just be learning the PID aspect of it out
of pure curiosity.

So far... the project at hand is going slowly but surely.
Problem. High humidity.
Source. Oversized equipment.
Lack of dehumidify controls/equipment
Motorized outside air damper not connected. Preset for full open. Assuming 25% outside air. (25% kept coming up when researching the damper)

Equipment is running correctly.
Unit way over sized when nobody is in the courtroom.
The P-link/CCN brings on 1st stage (10 ton) and keeps it on for a minimum amount of time.
After a delay (maxed at 5 minutes) the second stage comes on and it stays on for a minimum amount of time (think its set for 3 minutes)
After both stages have finished their minimum runtime, the controller thinks about what it needs to do via the PID algorithm.

Although I lack the equipment to plot the room temp.
It's looking much like this.

Minute Temperature...........Note: OCSP=74 OHSP=70
....1..........76...................Stage One Compressor ON
....2..........76
....3..........75
....4..........75...................Stage Two Compressor ON
....5..........74
....6..........73
....7..........72
....8..........71
....9..........70...................Stage Two Compressor Finishes Min ON time
....10.........69..............PID algorithm kicks in. Turns Both compressors OFF
....11.........69
....12.........69
....13.........69
....14.........70

As you can see, the room temp gets too cold before it all shuts down.
This is another prob I've been trying to correct in the process.


I have added a delay on make timer for Y2 and have my
timer maxed out.
This gives the unit a total of ~22 minutes before allowing the 2nd stage to come on.

Here's what it does after adding the delay timer
85 degree outdoor
Unoccupied
Compressor one comes on
Runs first stage for 13 minutes
Compressor one turns off
compressor two never has the chance to come on now

BUT
This is still not enough time to remove any humidity


We are going to replace the current room air temp sensor
with one that senses CO2.
Going to wire in the motorized damper to the P-link
so it will open when C02 is present.
The motorized damper does not have a 4-20mA control.
I'll have to power it via the Exhaust Fan relay (have to set it up in the configuration screens)
Normally, the P-link will modulate an economizer based on C02 levels.
And will power an Exhaust fan during this time.

Since my courtroom is not being used much, the humidity can be attributed to
the outside air damper remaining open.

I have tried setting the fan up to cycle on with heat/cool (ie AUTO mode)
rather than ON during occupied. AUTO during unoccupied.
The change resulted in a small reduction in humidity, but not enough.

Summary of work performed to reduce humidity.

Replaced restricted liquid line filter driers
Charged system correctly (charge on both circuits were off)
Confirmed good airflow (Referenced manufacturer data with measured static pressure. If I get a chance, I'm going to measure it with a flow hood. Only 12 supplies or so) Came up with 330 CFM / ton
P-link was using return air at unit for sensing room temp. Rewired to sense at
room temp sensor.
Set fan up for AUTO
Calibrated sensors
Adjusted louvers in supply air grilles. (All were blowing straight to the floor rather than across the ceiling. Checked air pattern with smoke puffer. I have air movement across ceiling, along wall, and to the floor. One vent was blowing air awfully close to the sensor on the wall. Hopefully this will give me even more run time.)

Will put in C02 Sensor and wire in outdoor damper next time I go out.

The system is capable of having either a Co2 sensor or a humidity sensor.
We thought about using the humidity sensor to cycle on one stage of heat.
But figured that would cause alot of complaints.
"Why the heck is the heat kicking on in the middle of the summer?"

If the C02 sensor approach does not reduce the humidity levels to the appropriate levels, we're going to have to add a stand alone humidity sensor
(Exhaust fan relay is the same one used for dehumidification.... so you have to use it for IAQ/CO2 or for Dehumidification) and add electric heat strips to
the supply duct. We can size the heat strips to more closely match the cooling.