SP Scientific ULTRA-COOL, Руководство оператора

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System Control Ultra-Cool
24 Rev 008, 01/12
© SP Scientific 2012
Remote RTD (rrtd = 0)
Defines the control point for system SP. Describes the control point for automatic
(integral) reset of the system. If "0", no remote RTD,
i.e ., control is from the local
(internal) RTD and the system will work normally using the internal sensor for control.
If rrtd is set to "1", control is from the (remote) external RTD and the system will adjust
its process to the remote (external) sensor. Should the external RTD be
unconnected, the system will automatically revert to local control. Note that the
proportioning (and derivative, if any) are always determined only by the internal
sensor. Only the external sensor adjusts the reset (integral) function.
The remote sensor itself is 2 wire. Within the (telephone) connector SP Scientific
provides, however, a connection is made to 4 wire. Therefore, it can be extended
without affecting its accuracy. Standard 6 pin modular (telephone) connectors are
used, providing ready access to extension cables at most electronic supply houses.
Control Parameters (PID)
Ramp Rate (rr = 0.00)
Programmed transition rate from old SP to new SP, in degrees per minute. To be
thought of more as a slew limiter, because the available ramp rate is obviously limited
by the warm-up/pulldown capacities of the heater and refrigeration.
Deadband (db = 0.0)
Temperature separation between Cool operation proportioning band and Heat
operation proportioning band, in degrees. Negative value indicates overlap in the
heat and cool bands.
Heat Proportioning Band (HPb = 0.01)
Width of the temperature span across which heat is proportionately applied to the
process, in degrees. In a heat only mode this would equate to ±2 degrees from
setpoint. In this system (heat/cool operation) the band is offset below setpoint and
then further shifted up or down by the Deadband/overlap parameter.
Cool Proportioning Band (CPb = 5.00)
In degrees, same as HPB but applied to refrigeration operation above setpoint.
Integral Time (It = 15.0)
Integral (Automatic Reset) time, in seconds. Time constant for adjustment of
proportioning action to correct deviation from setpoint.
Derivative Time (dt = 0.0)
Derivative (Rate of Change adjustment) time, in seconds. Time constant for
adjustment of proportioning action to reduce the slew rate of the process as it
approaches SP. Derivative time is automatically limited to 1/4 of the Integral Time It.
Cool Cycle Time (CCt = 2.5)
Period of operation of the cool/bypass refrigeration valves, in seconds. The period
(total time on and off) may never be less than two seconds, to reduce wear of the
solenoids and valves. Additionally, the duration of either On or Off is never less than
0.25 seconds. Should a very unbalanced proportioning action be required by the
process characteristics, the CCt period will automatically extend to meet this
minimum.