Watlow Series F4S/D - Manual (Page 74)

6 . 1 0 ■ F e a t u r e s Wa t l o w S e r i e s F 4 S / D
Advanced Features
Boost Heat and Boost Cool
The boost heat feature uses a digital output to turn
on an additional heater to speed up the heating. As
the process temperature approaches the set point,
the boost heat output switches off so that the pro-
cess temperature doesn’t overshoot the set point.
Boost cool uses a digital output to speed up the
cooling process, typically by activating a solenoid
valve that releases liquid nitrogen.
For either boost heat or boost cool, set Boost % Pow-
er to define the power level that must be exceeded
before the boost output is activated. Use a positive
value for heating, a negative value for cooling.
To prevent the output from cycling and to extend
hardware life, define Boost Time Delay in seconds
to set the minimum period of time that the output
will remain off after an on cycle.
The Series F4 uses digital output 6 for boost heat
and digital output 7 for boost cool. Hysteresis for
boost heat and cool is fixed at 5%.
Location in software: Setup > Digital Output x (6 or 7).
Figure 6.10a — Boost Heat and Boost Cool.
Boost Cool
Boost Percent
Power = 85%
Off
On
0%
-85%
-100%
Boost Delay Time = 30 Seconds
Time In Seconds
Cool
% Power
Boost Heat
Boost Percent
Power = 85%
Boost On Delay
= 30 Seconds
Off
On
100%
85%
0%
Time In Seconds
Heat
% Power
Compressor Control
The compressor control can save wear on a com-
pressor and prevent it from locking up from short
cycling. A bypass valve operated by a control output
regulates how the process is cooled, while a digital
output switches the compressor on and off.
The Series F4 uses digital output 8 for compressor
control. Compressor On % Power sets the power
level that will switch the compressor on. Compres-
sor Off % Power sets the power level that will
switch the compressor off.
The compressor will not turn on until the output
power exceeds the Compressor On % Power for a
time longer than the Compressor On Delay. The
compressor will not turn off until the output power
exceeds the Compressor Off % Power for a time
longer than the Compressor Off Delay.
Location in software: Setup Page > Digital Output 8.
Figure 6.10b — Compressor Power.
0% Compressor
On Power
Off
On
100%
2%
0%
-100%
Compressor On Delay = 45 Seconds
Compressor Off Delay = 20 Seconds
2% Compressor
Off Power
Time In Seconds
% Power
Heat
Cool
Compressor