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CoMMUNiCATioNS AND DiSplAYS
Two modes of communications are available to the R7910.
1.
The R7910 has two RS485 communication ports for
ModBus that allows for interfacing to one or all R7910s of
a system and presents them individually to the user. The
S7999B System Operator interface is a color touchscreen
displays used for configuration and monitoring of the
R7910A. Control Operation and display status in both test
and graphical modes can be shown along with the ability to
setup. The R7910 can also be remotely reset through the
S7999B display.
2.
Either ModBus RS485 communication port can be used to
allow configuration and status data to be read and written
to the R7910. Support a Master S7999B or a Building
Automation master to control the R7910 to respond to
a single ModBus address to service the requests of the
ModBus master in a Lead/Lag arrangement.
The local S7910 Keyboard display, the S7999B System Operator
interface, and the S7999C Local Operator Interface are optional
components.
The S7999B (or the DSP3944 which is a portable S7999B) or is
required configuration of the parameters of the R7910 but is not
needed for the operation of the system once configured.
SpeCiFiCATioNS
1.
Electrical Ratings:
Operating voltage
• 24VAC (20 to 30 VAC, 60 Hz ±5%)
• 30 amps (Single Heat Exchanger)
• 60 amps (Double Heat Exchanger)
Connected Load for Valve and annunciator functions:
• 24VAC, 60Hz
• 120VAC (+10%/-15%), 60Hz (±5%)
• Model Specific
2. Corrosion:
• R7910A must not be used in a corrosive environment.
3. Operating Temperature: -4°F to 150°F (-20°C to 66°C)
4. Storage/Shipping Temperature: -40°F to 150°F (-40°C to
66°C).
5. Humidity:
• Up to 95% Relative Humidity, noncondensing at 104°F for
14 days. Condensing moisture may cause safety shutdown.
6. Vibration: 0.0 to 0.5g Continuous (V2 level)
7. Enclosure: Nema 1/IP40.
8. Approvals:
Underwriters Laboratories, Inc. (UL): Component Recognized:
File No. MP268 (MCCZ)
• R7910 is certified as UL372 Primary Safety Controls.
• The R7910 is certified as UL353 Limit Rated device when
using part number 50001464 dual element limit rated
NTC sensors.
CSD-1 Acceptable.
Meets CSD-1 section CF-300 requirements as a Primary Safety Control.
Meets CSD-1 section CW-400 requirements as a Temperature
Operation control.
Meets CSD-1 section CW-400 requirements as a Temperature
High Limit Control when configured for use with 10 kohm NTC
sensors.
Federal Communications Commission, Part 15,
Class B. Emissions.
bUrNer CoNTrol operATioN
SAFeTY ShUTDoWN oF bUrNer CoNTrol FUNCTioNS
Safety Shutdown (Lockout) occurs if any of the following occur
during the indicated period:
1.
iNiTiATe perioD:
a. A/C line power errors occurred.
b. Four minute INITIATE period has been exceeded.
2. STANDbY perioD:
a. Flame signal is present after 240 seconds.
b. Preignition Interlock is open an accumulative time of
30 seconds.
c. Interlock Start check feature is enabled and the Interlock
String (including Airflow Switch) is closed for 120 seconds with
the controller closed. (jumpered or welded Interlock).
d. Main Valve Terminal is energized.
e. Internal system fault occurred.
3. prepUrGe perioD:
a. Preignition Interlock opens anytime during PREPURGE period.
b. Flame signal is detected for 10 seconds accumulated time
during PREPURGE.
c. Purge Rate Fan RPM or High Fire Switch fails to close within
four minutes and fifteen seconds after the firing rate motor
is commanded to drive to the high fire position at the start
of PREPURGE.
d. Light off Rate Fan RPM or Low Fire Switch fails to close
within four minutes and fifteen seconds after the firing rate
motor is commanded to drive to the low fire position at the end
of PREPURGE.
e. Lockout Interlock (if programmed) does not close within
10 seconds.
f. Lockout Interlock opens during PREPURGE.
g. Pilot Valve terminal is energized.
h. Main Valve terminal is energized.
i. Internal system fault occurred.
4. pre-iGNiTioN TiMe
a. Lockout Interlock opens.
b. IAS Purge and Ignition enabled and the Interlock opens.
c. Preignition Interlock opens.
d. Pilot Valve terminal is energized.
e. Main Valve terminal is energized.
5. piloT FlAMe eSTAbliShiNG perioD (pFep):
a. Lockout Interlock opens (if enabled).
b. Pilot Valve terminal is not energized.
c. No flame is present at the end of the PFEP, or after programmed
number of retry attempts.
d. Main valve terminal is energized.
e. Internal system fault occurred.
14
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