Issue
Assistance is required to create this programme.
Environment
- Sigma
- Programme
- Chiller control
- Prog points
Cause
This programme has been attempted, but does not operate as required.
Resolution
The programme must control 5 chillers in a fixed sequence.
There must be a delay of 20 minutes between starting chillers, (configurable).
The temperature differential from zero to all chillers operating must be adjustable.
The suggested programme is as follows:
10 XFlo = POINT 0|144 - POINT 0|140
20 IF XFlo <= 0.000000 THEN XFlo = 0.000000
30 IF XFlo >= POINT 0|141 THEN XFlo = POINT 0|141
40 XFlo = ( XFlo / POINT 0|141 ) * 100.000
50 XInt = 0
60 IF XFlo >= 20.0000 THEN XInt = XInt + 1
70 IF XFlo >= 40.0000 AND YInt >= 1 THEN XInt = XInt + 1
80 IF XFlo >= 60.0000 AND YInt >= 2 THEN XInt = XInt + 1
90 IF XFlo >= 80.0000 AND YInt >= 3 THEN XInt = XInt + 1
100 IF XFlo >= 100.000 AND YInt >= 4 THEN XInt = XInt + 1
110 IF TIME LEFT THEN GOTO 180
120 IF XInt > YInt THEN GOTO 150
130 YInt = XInt
140 GOTO 190
150 ZInt = INT ( POINT 0|142 ) * 60.0000
160 SET TIMER ZInt
170 YInt = YInt + 1
180 IF XInt < YInt THEN SET TIMER 0
190 RETURN VIA TEXT 92 VALUE FLOAT ( YInt )
Objects:
- 140 - SPA Object - Setpoint
- 141 - SPA Object - Differential required - 0 chillers to 5 chillers (degrees over which all chillers switch on)
- 142 - SPA Object - Delay time in minutes required.
- 144 - AI Object - Chillers Return Temperature
Link this programmable object to the chiller commands, using the hysteresis option.
On each chiller command object, enable the hysteresis option, setting will be as below.
- Chiller 1 - hysteresis low setting 0.1 and high setting 0.9.
- Chiller 2 - hysteresis low setting 1.1 and high setting 1.9.
- Chiller 3 - hysteresis low setting 2.1 and high setting 2.9.
- Chiller 4 - hysteresis low setting 3.1 and high setting 3.9.
- Chiller 5 - hysteresis low setting 4.1 and high setting 4.9.
For a copy of the above text, click here.