User Manual

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Uncontrolled system
If powered without regulation, a heater will rise in temperature until
heat losses (increasing with temperature) equal heat input. This may be
acceptable in rare situations, but normally is avoided because the equilibrium
temperature is highly unpredictable. In most cases the heater temperature
needs to be controlled. This allows the heater to ramp up to setpoint faster
without fear of overshooting and burning out the heater.
On/off control
On/off is the most basic form of control: Full power on below setpoint,
power off above setpoint. Electronic on/off controllers offer faster reaction
time and tighter control than thermostats. All on/off controllers have
a differential (hysteresis or dead band) between the on and off points
to reduce rapid cycling and prolong switch life. With on/off control,
temperature never stabilizes but always oscillates around the setpoint.
Proportional control
A proportional controller reduces power as the heater approaches
setpoint. This reduces oscillation for steadier control. Note that most
controllers are “time proportioning,” where they scale power by rapid on/
off switching. Short cycle times usually require a solid state relay for power
switching. Simple proportional controllers can experience “droop” where
the temperature settles at a point near the setpoint but not exactly on it.
PID controllers
Proportional/Integral/Derivative controllers solve the problem of droop
and otherwise improve control accuracy through advanced digital
algorithms. They have various tuning parameters for best control, but
typically have some preset modes suitable for most situations.
Temperature Controllers
Choose the control method that works best for your application
Desire
d
operatin
g
temperature
Setpoint
Droop
Minco controller model Control method Supply power Sensor input Controlled output
CT325 On/off 4.75–60 VDC
PD: 100 W platinum RTD
PF: 1000 W platinum RTD
TF: 50k W thermistor
Same as supply power
CT425
PID, proportional,
on/off (selectable)
CT425A: 120 VAC
CT425B: 10.5-60 VDC
CT425C: 240 VAC
PD: 100 W platinum RTD
PF: 1000 W platinum RTD
Same as supply power
Custom Control Solutions
In high volume applications, a specially designed controller
often gives the best performance and price. Controllers can
be standalone devices or embedded in other electronics,
allowing you to monitor and control your system
automatically.
Contact Minco today and learn how we can help configure
the perfect product for your application.
Choose the Right Controller
The following table illustrates the differences between
the CT325 and the CT425.