1. Maintains Suction Superheat Anticipates Changing Conditions
MCS FAST SSH
Maintains Suction Superheat
and
Anticipates Changing Conditions
Revised 1.0-Q June 19, 2018

2. Design Criteria Hold Superheat to a Target
Teach itself valve starting position
Reduces Config Setup to only 10 Standard Set Points
Fine Tuning with only 3 Adjustable Set Points
Eliminate Low Superheat Safeties
Eliminate Low PSI Safeties

3. System Requirements
1. Requires MCS-Config Version 18.00V or greater.
2. Requires MCS-Connect Version or greater.
3. Requires Magnum HVAC/RTU firmware Ver P hex or greater.
4. Requires Config Type 17.

4. Description of Suction Superheat (134A)
Suction Pressure Transducer 38 psi
At 38 psi, from psig to
Degrees F, Temp is 43 °F
Suction Temperature Sensor 58 °F
Condenser
SH = 58 °F - 43 °F = 15 °F
EXV
Evaporator

5. Fast SSH Set Point Categories DO NOT DO ANY FILTERING ON
There are Four (4) Groups of Fast SSH Set Points
Control - This consist of 2 set points that should have standard values for each model
Adjustment- This consist of 3 set points used for Fine Tuning
Safety- This consist of 3 set points that should have standard values based on model
Timing- This consist of 2 set points that should have standard values based on SH type
DO NOT DO ANY FILTERING ON
CONTROLLING SENSOR

6. Config Control Set Points (2)
SP#
NAME
DESCRIPTION
SP VALUE FIELD
SP TIME FIELD 9
FAST SH TRGT
TARGET
SUPERHEAT TARGET
Usually 10 to 12 F
# SECONDS SH ROC
Set to 1 second 10
FAST SH ZONE
DESIGN CTL RANGE
± SH DEGREES FAST ZN
Usually 2.0 F
ADJ. MPLY FAST ZONE
Usually 1
SP 9 VALUE FIELD SUPERHEAT TARGET
TIME FIELD NUMBER SECONDS ROC LOOKING AT (set to 1 for FAST SSH)
SP 10 VALUE FIELD DEFINE ZONE TO MAINTAIN
TIME FIELD IFGREATER THAN 1, MULTIPLER USED WITHIN THIS ZONE

7. Config Adjustment Set Points (3)
SP#
NAME
DESCRIPTION
SP VALUE FIELD
SP TIME FIELD 12
SH ADJUST
DISTANCE TO TARG
ADJ BASED ON SH
USUALLY 0.1
NOT USED 13
ROC ADJUST
CURRENT ROC
ADJ BASED ON ROC
USUALLY 0.1 to 1.0
NOT USED 14
LIMIT ADJUST
MAX ADJUSTMENT
LIMIT IN FAST ZONE
USUALLY 0.4
LIMIT Above 3 (Fast Zone)
USUALLY 15
SP 12 VALUE FIELD ADJUSTMENT AS FUNCTION OF CURR SH TO SH TARGET
SP 13 VALUE FIELD ADJUSTMENT AS FUNCTION CURRENT ROC
SP 14 VALUE FIELD LIMIT ADJUSTMENT TO THIS VALUE WHILE IN FAST ZONE
TIME FIELD LIMIT ADJ TO THIS VALUE WHEN OUTSIDE FAST ZONE
KEEP VALUES LOW FOR FAST SUCT SH, WE ARE ADJUSTING EVERY SECOND

8. Config Safety Set Points (3)
SP#
NAME
DESCRIPTION
SP VALUE FIELD
SP TIME FIELD 15
EXV MIN %
MIN VLV %
MIN VLV % COMP ON
USUALLY 5% / HI HGB
NOT USED 16
EXV MAX %
MAX VLV %
MAX VLV % COMP ON
USUALLY 100%
NOT USED 17
LO SUPERHT
LOW SH SAFETY
SH<VALUE TM SPECIFIED
USUALLY 2 F
TM BLW BEFORE SAFETY
USUALLY 45 SEC
SP 15 VALUE FIELD MIN VALVE % USUALLY 5, BUT HIGHER WITH HOTGAS BYP
SP 16 VALUE FIELD MAX VALVE % USUALLY 100
SP 17 VALUE FIELD SPECIFIES LOW SUPERHEAT SAFETY VALUE
TIME FIELD IF BELOW VALUE FOR SPECIFIED TIME, CAUSES SAFETY

9. Config Timing Set Points (2)
SP#
NAME
DESCRIPTION
SP VALUE FIELD
SP TIME FIELD 19
EXV DELAY
CALC TME FAST ZN
FAST ZONE CALC TIME
USUALLY 1 SEC
NOT USED 20
EXV START TM
MAX TME STARTUP
< 90 SECS-FIXED START
>= 90 SECS-CALC START
NOT USED
SP 19 VALUE FIELD SPECIFIES FREQUENCY OF FAST SUPERHEAT
TIME FIELD HOLD DEAD BAND WHEN ROC = 0 (VER 17.25F)
SP 20 VALUE FIELD FUNCTION OF COMP TYPE,
STD = 120 SEC, TURBCOR = 300 SEC (VER 17.25F)

10. Steps to Modify a Config to Fast SSH
Open Cfg to modify using MCS-Config18.00Q
Go to Circuit Base and select Fast SSH for EXV type
Go to Set Points (The FAST SSH values, in this example, are set to MCS Standards)
SP 11 must be Non-Active
Set all items in value field to your company standards
Set all values in Time(sec) to your company standards
Set all values in Lockout Delay(hrs) to your company standards
Set all values in Safety Down Time (min) to your company standards
SP 18 must be Non-Active
Set SP , 69, 70, 71 & 72 to Non-Active

11. Modify a Config to Fast SSH (continued)
Next bring up Relay Output
EXV Load & Unload adjust must not be setup here
Nominal tonnage must not be setup here
Bring up Setup Screen and increase SI by 3 for User Logic Statements
(If required)
Bring up SI screen to create User Logic Statements
Create User Logic for Target +
Create User Logic for Target –
Create User Logic for Comp SH (You need to create one for each comp
Change Revision Number in System tab to save with new Revision #
Test

12. SI Config Changes (info only)
Create User Logic EXV SH each circuit (watch if 2 EXV’s per circuit)
Create User Logic Target + & Target - (Point to Set Points 9 & 10)
Setting up the above user logic statements will allow you to setup and view a live graph, In MCS-Connect. This way you can see results of any adjustments you make.
When making any adjustments you should wait a minimum of 5 minutes to evaluate results.

13. Setting up MCS-Connect for Live Graph
1. Using windows functions move MCS-Connect blocks to desired position 
2. Using Workspace tab save window just created 

14. Building a Live Graph using MCS-Connect
1. Select Live Graph tab at top
Select add a graph
When prompted select Number of points, select 4
Change point 1 to Analog Outputs and select EXV 1 %
Point 2 Sensor Input select Suct SH 1
Point 3 Sensor input select Target +
Point 4 Sensor Input select Target - 
Set X Axis span to minimum of 300 seconds
Set Y Axis max to max valve % expected
Now Submit

15. Positioning Graph in MCS-Connect
1. Using windows functions move Graph blocks to upper left space open 
2. Using windows functions extend Graph to fill space available

16. Positioning Graph in MCS-Connect
Using Windows function position graph in left open area setup
Using Window functions expand graph to fit space

17. Saving Live Graph
1. To save the New Live Graph click on the Live Graph tab 
2. Click on Save A Graph option and save

18. Fast Suction SH F / PSI Setup
Sp 9 Fast Sh Trgt 11.0 Degrees F
Sp 10 Fast Sh Zone 2.0 Degrees F
Sp 14 Limit Adjust 0.3 Percent & 1.5 Percent (Assumed Decimal 1.5)
Sp 17 Lo Superheat 2.0 Degrees F
Sp 20 EXV Start Time If < 90 seconds - Start time fixed
If >= 90 seconds - Start time calulated

19. Fast Suction SH C / BARS Setup
Sp 9 Fast Sh Trgt 6.0 Degrees C
Sp 10 Fast Sh Zone 1.2 Degrees C
Sp 14 Limit Adjust 0.2 Percent & 1.5 Percent (Assumed Decimal 1.5)
Sp 17 Lo Superheat 1.0 Degrees C

20. Fast LEVEL SH Setup Sp 9 Fast Lvl Trgt 36 Percent
Sp 10 Fast Sh Zone 4.0 Percent
Sp 14 Limit Adjust 0.2 Percent & 1.5 Percent (Assumed Decimal 1.5)
Sp 17 Lo Superheat 1.0 Degrees C

21. Fast Sub Cooler SH Setup
SETPOINT NAME VALUE FIELD TIME FIELD
SP 65 FAST SC TARGET 18.0 DEGREES F
SP 66 FAST SC FAST ZN 2.0 DEGREES F
SP 67 FAST SC SH ADJ & ROC 0.1 SH ADJ 0.1 ROC ADJ (ASSUMED 1 DECIMAL)
SP 68 FAST SC SH LIMITS 0.4 MAX CLOSE ADJ 0.1 MAX LARGE ADJ (ASSUMED 1 DECIMAL)
SP 69 FAST SC MIN/MAX V 2.0 MIN VLV % 100.O MAX VLV % (ASSUMED 1 DECIMAL)
SP 70 FAST SC LOW SH 5.0 DEGREES F
SP 71 FAST SC EXV DELY 1 SECOND
SP 72 FAST SC START TIME 5 SECONDS

22. Compressor Low Suction Control Set Point
Set Points 77, 78 and 79 define when special control will occur to the compressor based on Low Suction Pressure
SP 77- Defines when Low Suction safety occurs and based on the time field how long before the system will go into that safety
SP 78- Defines at what value above the Low Suction safety the system will take corrective action, if available. The Time field in this Set Point defines how long to wait before starting corrective action.
SP 79- Defines at what value above the Low Suction SP the system is considered safe and can start to reload
This Set Point is not a function of FAST SSH
It is defined here since it will change the speed of the compressor if the FAST SSH is not able to correct the low suction within the time frame specified.

23. Critical Timing & Watching Results Fast SSH
Make one adjustment at a time and wait minumin 5 minutes, watching results on MCS-Connect with Live Graph.

24. What to Adjust in Fast SSH
Assuming you have developed a standard for each type of Superheat you only have 3 Control Set Points. (SP 12, 13 and 14)

25. Adjusting “SH ADJUST” in Fast SSH
SP#
NAME
DESCRIPTION
SP VALUE FIELD
SP TIME FIELD 12
SH ADJUST
DISTANCE TO TARG
ADJ BASED ON SH
USUALLY 0.1
NOT USED
SH ADJUST is a function of how far we are from our target.
Recommend standard is 0.1 (This is the minimum value)
If the “Live Graph”, in MCS-Connect, shows the SH to be consistently below the target, increase this value to 0.2

26. Adjusting “ROC ADJUST” in Fast SSH
SP#
NAME
DESCRIPTION
SP VALUE FIELD
SP TIME FIELD 13
ROC ADJUST
CURRENT ROC
ADJ BASED ON ROC
USUALLY 0.1
NOT USED
ROC ADJUST is a function of the current slope of the SH.
Recommend standard is 0.1 (This is the minimum value)
If the “Live Graph”, in MCS-Connect, shows the SH to be oscillating, increase this value to 0.2

27. Adjusting “LIMIT ADJUST” in Fast SSH
SP#
NAME
DESCRIPTION
SP VALUE FIELD
SP TIME FIELD 14
LIMIT ADJUST
MAX ADJUSTMENT
LIMIT IN FAST ZONE
USUALLY 0.2
LIMIT Above 3X (Fast Zone)
USUALLY 15
LIMIT ADJUST is a damping control with two (2) control areas
The value field limits the adjustment when within the Fast Zone
The time field limits the adjustment when outside the fast zone
Recommend the “VALUE FIELD” be 0.2
Remember adjustments are being made every second (SP 19)
If the SH does not stay within the FAST ZONE you can increase this value.
Recommend the “TIME FIELD” be 15
If the SH take too long to recovery when outside the FAST ZONE you can increase this value. (SET HIGH TO HANDLE TANDEM COMP’s)

28. Adjusting “LIMIT ADJUST” in Fast SSH (cont.)
In FAST SSH, SET POINT 14 - ‘LIMIT ADJ’, start with the setting of 0.2 (equal to 2 in the magnum) as shown above.
The TIME FIELD in limit adj – is set high to accommodate tandem scrolls. Example Time field shows 15, see above.
Remember to increase these number by small increments keeping the Time field usually higher than the Value field and view the changes in an MCS-CONNECT Live Graph before making additional changes.

29. Connect Graph FSH Startup
Comp Starts then 5 seconds later EXV goes to Starting Position
At 31 sec FAST SSH looking for Target + 5°F ( = 17.0)
If FAST SSH takes control between 45 to 90 seconds no EXV starting chg

30. Connect Graph FSH Startup (cont)
At 55 sec we reach 17.0°F SH & EXV State goes from STARTUP to Hold
FAST SSH now starts adjusting based on requirements
No change to starting valve position since control in less than 90 sec

31. Connect Graph FAST SSH Increasing Fan Speed
Fan speed was increasing from 80 to 95% with no noticeable effect

32. Connect Graph FAST SSH 5% Increase Comp Speed
Comp speed was increased by 5% & FAST SSH maintained SH within Fast Zone. FAST SSH recovered to SH Target within 65 seconds
If SH goes outside FAST ZONE and recovery is too long or too short adjust SP 14 Time field.

33. (Support, Literature, App Notes)
MCS FAST SUPERHEAT
For additional information please visit our website
Application Note 116
(Support, Literature, App Notes)
Or call MCS at
5580 Enterprise Pkwy.
Fort Myers, FL 33905
Office:
Fax: