Maintains Suction Superheat and Anticipates Changing Conditions MCS FAST SSH www.mcscontrols.com Revised 1.0-Q January 1, 2020
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
System Requirements 1. Requires MCS-Config Version 18.00V or greater. 2. Requires MCS-Connect Version 18.10.09 or greater. 3. Requires Magnum HVAC/RTU firmware Ver. 17.25P hex or greater. 4. Requires Config Type 17.
Description of Suction Superheat (134A) Suction Pressure Transducer 38 psi At 38 psi, from psig to Degrees F, Temp is 43 °F 38 43.00 Suction Temperature Sensor 58 °F Condenser SH = 58 °F - 43 °F = 15 °F EXV Evaporator
Fast SSH Set Point Categories • 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
Config Control Set Points (2) SP# NAME SP VALUE FIELD SP TIME FIELD DESCRIPTION FAST SH TRGT SUPERHEAT TARGET Usually 10 to 12 F # SECONDS SH ROC Set to 1 second TARGET 9 10 FAST SH ZONE ± SH DEGREES FAST ZN Usually 2.0 F ADJ. MPLY FAST ZONE Usually 1 DESIGN CTL RANGE 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
Config Adjustment Set Points (3) SP VALUE FIELD SP TIME FIELD SP# NAME DESCRIPTION ADJ BASED ON SH USUALLY 0.1 NOT USED SH ADJUST DISTANCE TO TARG 12 13 ROC ADJUST ADJ BASED ON ROC USUALLY 0.1 to 1.0 NOT USED CURRENT ROC 14 LIMIT ADJUST LIMIT IN FAST ZONE USUALLY 0.4 LIMIT Above 3 (Fast Zone) USUALLY 15 MAX ADJUSTMENT 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
Config Safety Set Points (3) SP# NAME SP VALUE FIELD SP TIME FIELD DESCRIPTION EXV MIN % MIN VLV % COMP ON USUALLY 5% / HI HGB NOT USED MIN VLV % 15 16 EXV MAX % MAX VLV % COMP ON USUALLY 100% NOT USED MAX VLV % 17 LO SUPERHT SH<VALUE TM SPECIFIED USUALLY 2 F TM BLW BEFORE SAFETY USUALLY 45 SEC LOW SH SAFETY 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
Config Timing Set Points (2) SP# NAME SP VALUE FIELD SP TIME FIELD DESCRIPTION EXV DELAY FAST ZONE CALC TIME USUALLY 1 SEC NOT USED CALC TME FAST ZN 19 20 EXV START TM < 90 SECS-FIXED START >= 90 SECS-CALC START NOT USED MAX TME STARTUP 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)
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 65. 66. 67, 69, 70, 71 & 72 to Non-Active
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
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.
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
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
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
Positioning Graph in MCS-Connect • Using Windows function position graph in left open area setup • Using Window functions expand graph to fit space
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
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
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
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
Fast Sub Cooler SH Setup • SETPOINTNAMEVALUE FIELDTIME 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
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.
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.
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)
Adjusting “SH ADJUST” in Fast SSH SP# NAME SP VALUE FIELD SP TIME FIELD DESCRIPTION SH ADJUST ADJ BASED ON SH USUALLY 0.1 NOT USED DISTANCE TO TARG 12 • 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
Adjusting “ROC ADJUST” in Fast SSH SP# NAME SP VALUE FIELD SP TIME FIELD DESCRIPTION 13 ROC ADJUST ADJ BASED ON ROC USUALLY 0.1 NOT USED CURRENT ROC • 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
Adjusting “LIMIT ADJUST” in Fast SSH SP# NAME SP VALUE FIELD SP TIME FIELD DESCRIPTION 14 LIMIT ADJUST LIMIT IN FAST ZONE USUALLY 0.2 LIMIT Above 3X (Fast Zone) USUALLY 15 MAX ADJUSTMENT • 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)
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.
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 (12.0 + 5.0 = 17.0) • If FAST SSH takes control between 45 to 90 seconds no EXV starting chg
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
Connect Graph FAST SSH Increasing Fan Speed • Fan speed was increasing from 80 to 95% with no noticeable effect
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.
MCS FAST SUPERHEAT For additional information please visit our website www.mcscontrols.com Application Note 116 (Support, Literature, App Notes) Or call MCS at 239-694-0089 5580 Enterprise Pkwy. Fort Myers, FL 33905 Office: 239-694-0089 Fax: 239-694-0031 www.mcscontrols.com