Honeywell VRX180 Manual De Usuario

 

Table 4-10   Loop Prompts (continued) 

RATE#1 &            

RATE#2 

0.02-10.00 minutes 

Modifies the loop output based on the rate of change of the 
process variable. The output is modified by a value that 
assumes the rate of change of the process variable will 
continue for the time period specified. Enter a starting value 
or OFF at the time of configuration. The value may be altered 
Online for final loop tuning. For loops with dual tuning, Rate 1 
is the rate for the first set of tuning parameters. Rate 2 is for 
the second set.  (Variable Rate1 is available by programming 
a constant's Destination with RT. Program Constants, Section 
4.16.) 

RESET#1 & 

RESET#2 

0.005-99.99 repeats/minute 

Determines the period of time for a repeat of the proportional 
gain output. Enter a starting value at initial configuration. The 
value may be altered Online for final loop tuning. For loops 
with dual tuning, Reset 1 is the time for the first set of tuning 
parameters. Reset 2 is for the second set.  (Variable Reset1 
is available by programming a constant's Destination with RS.  
See Program Constants, Section 4.16.) 
A value of OFF may be entered to allow proportional-only 
control. When turned off, the manual reset value determines 
the loop output at set point. Bumpless manual to automatic 
transfer is canceled when proportional only control is 
selected. 

RESET LIMIT 

OFF or 100 to 200%. 

This value restricts the calculated integral value of the loop 
during Cold Start or on a manual-to-automatic transfer. 

RATIO BIAS 

 

Enter a bias value to be used in calculating the working set 
point of the ratio control loop. This is essentially a value that 
will be added to the product that results when RATIO 
SETPOINT is multiplied by the ratio loop’s wild variable input 
value. For example, in the fuel-air ratio control scenario 
introduced in the RATIO SETPOINT section, suppose fuel 
flow is the wild variable that measured to be 60. With the 
RATIO SETPOINT prompt set to 0.5, the result will be 30 
when the RATIO SETPOINT is multiplied by the fuel flow. If 
the RATIO BIAS prompt is then set to 10, the actual set point 
that the ratio loop will use to control air flow will be 30 + 10 = 
40. 
To make a ratio control loop’s working set point equal to: 
(RATIO SETPOINT  x Wild Variable value) + RATIO BIAS 
the loop’s working set point must be toggled to SP2 using the 
“SP (Set Point select)” key while viewing the loop’s ON LINE 
display. Refer to Figure 4-1.