33
®
•
THML SHK
(Thermal Shock Protection): This setpoint enables the thermal shock protection
function. The selections are
UNUSED
,
LOW FIRE
and
SEGMENT
.
•
LOW FIRE METHOD:
This method of cold start thermal shock protection is generally used
on Water Tube Boilers. The setpoints associated with this method of thermal shock protection
is:
•
THML EXIT
(Thermal Shock Exit Setpoint): The BurnerLogix will hold the Firing
Rate motor in the low fire (LF) position until the steam pressure (or water temperature)
reaches the Thermal Shock Exit Setpoint (
THML EXIT
). Once this steam pressure (or
water temperature) is reached, the firing rate motor is positioned according to the mod-
ulating control algorithm. See Figure 6.
•
THML LF%
(Low fire minimum): Use this selection to set the firing rate motor posi-
tion during the low fire method operation.
Note: If AUX1 is programmed for STNDBY WTR, Thermal Shock Protection - Low Fire Method
will control according to boiler water temperature and not steam pressure. See SEQUENCE OF
OPERATION - STANDBY WATER section.
FIGURE 10.
Cold Start Thermal Shock Protection - Low Fire Method
•
SEGMENT METHOD:
This method of cold start thermal shock protection is generally used
with Fire Tube Boilers. The setpoints associated with this method of thermal shock protection
are:
•
THML STRT
(Thermal Shock Start Point): Determines the start point for thermal
shock protection.
•
THML EXIT
(Thermal Shock Exit Point): Determines the exit point for thermal
shock protection.
•
THML OVRD
(Timed Override Per Segment Setpoint): Determines maximum time
BurnerLogix holds the firing rate for each segment before increasing to the next seg-
ment.
THML STRT and THML EXIT:
Once the burner cycle starts, the BurnerLogix will hold the firing
rate motor in the low fire position until the steam pressure (or water temperature) reaches the Ther-
mal Shock Start Point (
THML STRT
). The BurnerLogix then automatically divides the difference
between the high fire position and low fire position into sixteen (16) segments. The BurnerLogix
also divides the difference between the Thermal Shock Exit Point (
THML EXIT
) and Thermal
Shock Start Point (
THML STRT
) into sixteen (16) segments. The BurnerLogix will increase the fir-
ing rate motor by the value of one segment, and wait until the steam pressure (or water temperature)
increases by the amount of one segment. Once the steam pressure (or water temperature) increases
by the calculated amount, the BurnerLogix increases the firing rate motor by the value of one seg-
LOW
FIRE
STM SP = 100 PSI
CUT IN = 0
CUT OUT = 20
MOD RNGE = 30
10
20
30
40
HIGH
FIRE
100%
20mA
0%
4mA
50
60
70
80
90
100
110
120
130
THML EXIT = 40 PSI
STEAM PRESSURE (PSIG)
BOILER
FIRING
RATE MOTOR
THML EXIT
Содержание BurnerLogiX BLL510
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