Speedtrol; Emergency Shutdown; Freeze Protection - Daikin RoofPak RPS Series Installation And Maintenance Manual

SpeedTrol

™
(Not Available on Unit Sizes 015C to 030C)
Daikin's SpeedTrol system of head pressure control operates
in conjunction with FanTrol by modulating the motor speed
of the last condenser fan of each refrigeration circuit in
response to condenser pressure. By varying the speed
of the last condenser fan of each refrigeration circuit, the
SpeedTrol option allows mechanical cooling operation in
ambient temperatures down to 0°F (-18°C) provided the unit
is not exposed to windy conditions. The system designer is
responsible for assuring the condensing section is not exposed
to excessive wind or air circulation. SpeedTrol controllers
SC11 and SC21 sense refrigerant head pressure and vary the
fan speed accordingly. When the pressure rises, SpeedTrol
increases the fan speed; when the pressure falls, SpeedTrol
decreases the fan speed. The SpeedTrol controller's throttling
range is 140 to 200 psig (1212 to 1318 kPa) fixed.
The SpeedTrol fan motor is a single phase, 208/240-volt,
thermally protected motor specially designed for variable speed
application. Units with 460-volt power have a transformer
mounted inside the condenser fan compartment to step the
voltage down to 230 volts for the SpeedTrol motor. A portion of a
typical SpeedTrol power circuit schematic is shown in

Emergency Shutdown

The terminals 105 & 106 on TB2 can be used for any field
supplied component that requires a unit emergency shutdown.
When these terminals are used, the factory installed jumper
must be removed.
Figure 98: SpeedTrol Schematic
4L13
L1
4L14
L2
4L13
L1
4L14
L2
www.DaikinApplied.com
Figure
M11
F11
757-1
1 L
T1
759-1
3 L
832
T2
M21
F12
762-1
1 L
T1
764-1
3 L
865
T2

Freeze Protection

An optional freezestat is available on units with MicroTech III
control that have hot water, chilled water, or steam heating
coils. The sensing element is located on the downstream
side of the heating coil in the heating section of the unit. If
the freezestat detects a freezing condition and closes, the
MicroTech III controller takes different actions, depending on
whether the fans are ON or OFF. The freezestat is an auto
reset type of control; however, the controller alarm that it
causes is manually reset if the fan is on and auto reset if the
fan is OFF.
Fan ON Operation
If the freezestat detects a freezing condition while the fan is
on, the MicroTech III controller shuts down the fans, closes
the outdoor air dampers, opens the heating valve, and sets a
10-minute timer. The MicroTech III controller's active alarm is
"Freeze Fault."
When the 10-minute timer expires, the controller begins
checking the freezestat again. If the freezestat is open, the
heating valve closes. If the freezestat closes again, the heating
valve opens, and the 10-minute timer resets.
97.
The unit remains shut down until the "Freeze Fail" alarm is
manually cleared. Refer to the operation manual supplied with
the unit for information on clearing alarms
Fan OFF Operation
If the freezestat detects a freezing condition while the fan is off,
the MicroTech III controller opens the heating valve and sets a
10-minute timer. The MicroTech III controller's active alarm is
"Freeze Problem."
When the 10-minute timer expires, the controller begins
checking the freezestat again. If the freezestat is open, the
heating valve closes. If the freezestat closes again, the heating
valve opens, and the 10-minute timer resets.
When the freezestat opens again, the "Freeze Prob" alarm
automatically clears. This feature protects the coil and allows
the system to start normally after a cold night.
HCF11-S1
+NB
L1
T 1
SC11
M1
HCF11-S3
T 3
H738-2
1
H739-2
24V
2
3-2 3-1
1
24V
H741-2
2
H740-2
HCF21-S1
+NB
T 1 L1
SC21
M1
HCF21-S3
T 3
85
Unit Options
(OM 138
+NB
COND-FAN11
HCF11-1
L1
C11
HCF11-2
MTR
2 1
L2
HCF11-3
1 1 1 1 1 1 1 L3
+NB
COND-FAN21
HCF21-1
L1
C21
HCF21-2 MTR
2 1 L2
HCF21-3
1 1 1 1 1 1 1 L3
IM 926-3 • ROOFPAK APPLIED SYSTEMS
or OM 137).