Bryan Boilers Triple-Flex 150 ユーザーズマニュアル

 

Date:  

8-4-2010 

 

Revision: 0 

 

Form:  

2396

 

that: 
Drop-Stage detection time is used with 
DropStageDetectTimer 
In the descriptions below, the relevant 
parameter is referred to as LL – Drop Stage 
detection timeN}

. 

Drop-Stage method: 
Disable, 
Error threshold, 
Rate threshold, 
dError/dt and threshold, 
dRate/dt and threshold 
 
DROP-STAGE ERROR THRESHOLD: 
DEGREES 
This provides the error threshold as defined by 
the methods below. 
 
DROP-STAGE RATE OFFSET: -100% TO 
+100% 
This provides the rate offset threshold as 
defined by the methods below. 
 
LL boiler off options: 
Options disabled, 
Enable all boilers off (ABO) 
Enable lead drop-stage on error (LDSE) 
Enable both ABO and LDSE 
 
This provides options for customizing the way 
stages are dropped, as described below. 
 
LL ALL BOILERS OFF THRESHOLD: 
TEMPERATURE OR NONE 
When the LL boiler off options specifies "Enable 
all boilers off (ABO)" or "Enable both ABO and 
LDSE" then this parameter provides the boiler 
off threshold temperature that is used. In this 
case, if the temperature is the None value then a 
parameter error lockout occurs. 
 
Drop-stage methods Error threshold 
 
For error threshold staging, a stage is dropped 
when the  error becomes excessive based on 
degrees away from setpoint and time. 
 
DROP-STAGE CONDITION: 
- The modulating burner(s) is at its (their) 
minimum position per the rate allocation rules, 
- The operating point is above the setpoint by an 
amount  greater than or equal to Drop-stage 
error threshold 
 
When the Drop-stage condition is false then 
 

is set to zero. (If the 

condition  is true then DropStageDetectTimerN 
is not zeroed and thus  allowed to run.) If this 
timer reaches or exceeds Dropstage detection 
timeN 

then DropStageRequestN is true. 

 
RATE THRESHOLD 
For rate based staging, a stage is dropped 
based on the rate of the last stage. 
 
DROP-STAGE CONDITION: 

The modulating burner(s) is at a rate that is at 

or below the minimum modulation rate plus a 
rate offset. 
Examples: 
rate offset = 20% The Drop-stage condition will 
occur when the last stage is less than a 
threshold that is the minimum modulation rate 
plus another 20%. 
 
rate offset = 0% The Drop-stage condition will 
occur when the last stage is at the minimum 
modulation rate. 
 
rate offset = -20% The Drop-stage condition will 
occur if the last stage is at minimum modulation 
and there is 20% less rate to distribute than can 
be absorbed; that is, the rate allocator would like 
the minimum modulation rate to be lower than it 
is. 
 
To support this, the current Rate Alloction 
method asks for the current "Underflow rate" - 
see the Rate Allocator section. 
 
Boiler off options 
 
The  LL boiler off option controls two optional 
behaviors. One option is to enable the use of the 
LL all boilers off threshold 

and is abbreviated 

"ABO", and the other controls whether a lead 
boiler is affected by a drop-stage method based 
upon error, and is abbreviated as "LDSE". 
 
ALL BOILERS OFF - ABO: 
The ABO temperature provides a Burner Off 
threshold that essentially replaces the normal 
Burner Off threshold as given by the LL off 
hysteresis 

parameter; it is processed by the 

same logic block using some additional rules. 
 
If ABO is enabled then: 
• When the LL master operating point reaches or 
exceeds the ABO threshold this turns off LL 
master burner demand. 
• The Burner Off threshold provided by LL off 

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