Johnson Controls P266 Serie Instrucciones De Instalación página 7

Low-Speed Capacitor Mode
In some fan speed applications, a (user-supplied)
Low-speed capacitor (LSC) can be connected to the
P266 Series control's M3 triac and the controlled fan
motor (Figure 3 and Figure 4). The low-speed capacitor
is enabled at low voltages to enhance the fan motor
efficiency and performance. Set Low-speed Capacitor
mode to On when a low-speed capacitor is used.
Low-Speed Capacitor
Enabled
End
Voltage
Changeover Voltage
CV
Start
Voltage
LPM On
LPM
Off
0
Start
Pressure
Pressure at Sensor
Figure 6: Low-Speed Capacitor Operation
Note: The optional low-speed capacitor should be
equal in both the voltage range and the microfarad
value to the auxiliary capacitor supplied by the
manufacturer, but the capacitor must not exceed
15 microfarads.
Note: You must also set the Changeover Voltage
value when a low-speed capacitor is used in your P266
Series control application. See Changeover Voltage
Value and Determining Changeover Voltage Value for
more information on setting the Changeover Voltage
value.
Auxiliary Fan Stage Mode
You can set the P266 Series control to cycle (On/Off)
up to three additional (fixed-speed) fan motors or fan
stages in conjunction with the variable speed fan
controlled by the P266 Series control.
Three low-voltage circuits (Figure 2) can be wired to
control the auxiliary fan motor/stage starters. See
Table 2 for information on setting the number of
auxiliary fans used in your application.
6 P266 Series Single-Phase Condenser Fan Speed Control Installation Instructions
Low-Speed Capacitor
Disabled
End
Pressure
Figure 7 shows a P266 Series control application with
one auxiliary fan operating in conjunction with the
speed-controlled fan. When the condenser load
exceeds the output capacity of the speed-controlled
fan, the P266 Series control powers On the auxiliary
fan and shifts the speed-controlled (P266) fan to a new
start pressure.
Fan Throttling Range
Total
P266 Fan
Stage
Shift
1st
Stage
0
Start
Pressure
Pressure at Sensor
Figure 7: Speed-Controlled (P266) Fan Operating
with One Auxiliary (On/Off) Fan Stage
over the Entire Pressure Range
Auxiliary Fan Overlap Value
Auxiliary Fan Overlap value determines the pressure
range overlap (as a percentage of the total pressure
[throttling] range) between the fan stages set up on the
P266 Series control. The fan overlap value is equal for
all auxiliary fan stages set up on the control.
Increasing the Auxiliary Fan Overlap value decreases
the (On/Off) cycling rate of the auxiliary fans and
increases the pressure differential between auxiliary
fan stages (which increases the pressure range of each
auxiliary fan stage).
Note: If the P266 Series control is set for no auxiliary
fans, the Auxiliary Fan Overlap value is not used. See
Table 2 for information on setting the number of
auxiliary fans used in your application.
Changeover Voltage Value
The Changeover Voltage value determines the voltage
at which the P266 Series control enables and disables
the M3 triac and the low-speed capacitor (Figure 6).
See Determining Changeover Voltage Value.
% Fan
Overlap
Aux.Fan
Plus
P266 Fan
Output
Auxiliary
Fan
Output
End
Pressure