CEMP-E
TI 810-11
30 November 1998
(4) On a fall in temperature to its setpoint, low temperature protection thermostat TSL-XX-01
opens a set of closed contacts in the supply fan starter circuit, de-energizing the supply fan. The
auxiliary contacts of the supply fan starter de-energize relay R-XX-05, and the contacts of relay R-XX-05
in the return fan starter circuit de-energize the return fan. A set of open contacts in low temperature
protection thermostat TSL-XX-01 close, energizing relay R-XX-08 and lighting pilot light PL-XX-05. The
contacts of relay R-XX-08 energize relays R-XX-10 and R-XX-11. One set of the contacts of relay
R-XX-10 locks in relays R-XX-10 and R-XX-11, and another set de-energizes the supply fan. Relay
R-XX-11 de-energizes the return fan. To restart the fans after a low temperature shutdown, both the low
temperature thermostat TSL-XX-01, and the control panel must be manually reset. The control panel is
reset by momentarily depressing manual switch HS-XX-02.
(5) When smoke detector SMK-XX-01 or smoke detector SMK-XX-02 detects the presence of
smoke, its normally closed contacts in the supply fan starter circuit open, de-energizing the supply fan.
The auxiliary contacts of the supply fan starter de-energize relay R-XX-05, and the contacts of relay
R-XX-05 in the return fan starter circuit de-energize the return fan. Its normally open contacts close,
energizing relay R-XX-09. The normally open contacts of R-XX-09 close, energizing relays R-XX-10 and
R-XX-11. One set of contacts of relay R-XX-10 (line 17) locks in relays R-XX-10 and R-XX-11. The
other set of contacts of relay R-XX-10 (line 101) de-energizes the supply fan, and the contacts of relay
R-XX-11 de-energize the return fan. To restart the fans after a smoke alarm shutdown, smoke detectors
SMK-XX-01 and/or SMK-XX-02 and the control panel must be manually reset. The control panel is reset
by momentarily depressing manual switch HS-XX-02.
(6) Differential pressure gauge DPI-XX-01 across the filter provides local indication of filter
loading. On a rise in pressure drop across the filter to its setpoint, differential pressure switch DPS-XX-
01 turns on pilot light PL-XX-04.
(7) Temperature controller TC-XX-02, with its temperature transmitter TT-XX-04 in the cooling
coil discharge, through the contacts of relay R-XX-06 and current-to-pneumatic transducer IP-XX-02,
modulates cooling coil valve VLV-XX-01 to maintain its temperature setpoint. Relay R-XX-06 is
energized during the ventilation delay and occupied modes. During the unoccupied mode, R-XX-06 is
de-energized, cooling coil valve control is interrupted, and the valve closes.
(8) Hot deck temperature controller TC-XX-03, with its temperature transmitter TT-XX-05 in the
heating coil discharge, modulates hot deck heating coil valve VLV-XX-02 to maintain its temperature
setpoint. Controller TC-XX-04 with temperature transmitter TT-XX-02 in the outside air raises the
setpoint of controller TC-XX-03 on a fall in outside air temperature and lowers it on a rise in outside air
temperature.
(9) On a rising zone space temperature, thermostat T-XX-XX modulates damper actuator
DA-XX-XX to gradually close the zone damper to the hot deck and open it to the cold deck. The reverse
occurs on a falling zone space temperature.
(10) When the occupied contacts of time clock CLK-XX-01 open to end the occupied mode and
index the system to the unoccupied mode, relays R-XX-01 and R-XX-02 are de-energized and pilot light
PL-XX-01 is turned off. The contacts of relay R-XX-02 open, de-energizing the supply fan and placing
the system's night thermostat TSL-XX-02 in control of the supply fan, and, through interlock, in control of
the return fan. On a fall in space temperature to 13 degrees C (55 degrees F), the contacts of
TSL-XX-02 close, energizing both fans; on a rise in temperature to 16 degrees C (60 degrees F), the
contacts open, de-energizing the fans.
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