Tempco TEC-2500, Instruction Manual

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4–4 Ramp and Dwell
Ramp
The ramping function is performed during power up as well as any time the set point is
changed. Choose MINR or HRR for SPMD, and the unit will perform the ramping
function. The ramp rate is programmed by using RAMP, which is found in the user menu.
Example without dwell timer
Select MINR for SPMD, °C for IN1U, 1-DP for DP1, and set RAMP=10.0. SP1 is set to
200°C initially, then changed to 100°C 30 minutes after power up. The starting
temperature is 30°C. After power up, the process runs like the curve shown below:
Note: When the ramp function is used, the display will show the current process value.
However, it will revert to show the set point value as soon as the up or down key is
pressed for adjustment. Setting RAMP to zero means no ramp function at all.
Dwell
The dwell timer can be used separately or in conjunction with a ramp. If A1FN is set for
TIMR, alarm 1 will act as a dwell timer. Similarly, alarm 2 will act as a dwell timer if A2FN
is set for TIMR. The timer is programmed by using TIME which is in the user menu. The
timer starts to count as soon as the process reaches its set point, and triggers an alarm
when it times out. Here is an example.
Example without ramp
Select TIMR for A1FN, °F for IN1U, NODP for DP1, and set TIME=30.0. SP1 is set to
400°F initially, and corrected to 200°F before the process reaches 200°F. As the process
reaches the set point (i.e., 200°F), the timer starts to count. The TIME value can still be
corrected without disturbing the the timer before time out. TIME is changed to 40.0 28
minutes after the process has reached its set point. The behavior of the process value
and alarm 1 are shown below.