Libratherm offers Microcontroller based multiple Ramp/Soak Programmable PID Temperature Controller Model PRC-300 which is designed to improve reliability, accuracy, and control for all processing applications. It features Ramp and Soak functions (the capability to control the temperature and its rate of change over a predetermined time span). This PID SSR Temperature Controller PRC-300 offers a single profile of 16 steps that can be programmed into the memory with the user-friendly membrane keyboard. Separate displays are provided to monitor simultaneously; the Process temperature, Set temperature, and the Program number. They can also be used as single set point control when the profile control is not desired. They accept user-selectable standard temperature sensors like K, R, S, and B type thermocouples.
The Profile Control System offers both switching outputs in the form of SSR driver or Triac to drive external single or three-phase Solid-state relays or load contactors and linear analog control outputs in the form of (4-20)mA or (0-5)volt or (0-10)VDC, which can be used to control heater power through Thyristor Power Regulators (for an electrical heating system) or to control the position of a modulating motor valve (for oil or gas-fired heating systems). The analog outputs can be directly connected to Libratherm make single-phase/three-phase SCR based phase angle fired power controllers, which are ideally suitable for both resistive and inductive heating load. Additional 4 relays are also provided for time or temperature-dependent event outputs as per the system requirement. The programmed profile and other parameters are retained in the nonvolatile flash memory in the event of power failure.
To monitor the online temperature profile of the heating system, a serial communication port on the RS485 interface can also be optionally provided, the same can be connected to the computer.
|Design||Microcontroller based with 12 bit ADC and dual 12 bit DAC.|
|Input||Thermocouple type K, R, S, B, (user selectable) or RTD (Pt-100)|
|Range||Subject to the full range of the specified input.|
|Resolution||1°C Subject to the specified input type and range.|
|Indicating Accuracy||Better than ± 0.1% of the range ( by software linearization of curves)|
|Display||4 digit 0.5” for process value.|
|4 digit 0.5” for set value and other parameters.|
|Tuning||Manual tuning of PID values.|
|Control Algorithm||PID mode for heating control,
On/Off mode with programmable hysteresis.
|PID values||Proportional Band (P)= 0.0 to 100.0% of Span,
Integral value (I)= 0.00 to 5.00 resets/minute,
Derivative value (D) = 0.00 to 5.00 minutes
Cycle Time (CYC)= 2 to 100 seconds,
On/Off Hysteresis (HYSt)= 0 to 50 °C,
|Soft Start (rt) and||Built in power on soft start (rt) for analog output = 1 to 99 seconds.|
|Power Limit (PL)||Power Limit to restrict the analog control output = 1 to 100 %.|
|E.G. If control output is 0 to 5VDC and PL=80%, then control output range will be restricted to 0 to 4Volt (80% of 5Volt).|
|Control Outputs||a) DC pulses to drive external SSR,
b) (4-20)mA, RL max = 300 Ohms. Or
c) (0-5)VDC / (0-10)VDC, RL min = 10K ohms.
d) (4-20mA) retransmission output proportional to temperature (Optional)
|Ramp/Soak Steps||1 to 16 Steps. (No restrictions in programming – a ramp can be followed by a ramp and a soak can be followed by a soak).|
|Set Temperature||Programmable for each steps in the full range of the specified input.
In single set point or profile control mode.
|Time per each Ramp/Soak Step||1 to 540 mins. (9 Hrs. per step) Or
1 minute to 100 hours (Two or more steps can be combined for longer time duration).
|Run from desired step number (rFSn)||This rFSn facility allows user to skip the ramp/soak steps and
run the profile from the desired step number.
With servo start facility (to start the step from the current furnace temperature)
the rate of heating/cooling can be kept same.
|Program Hold Facility||Manual Hold or Auto Hold (Hold back feature for guaranteed Ramp/Soak facility) dHLd= 0 to 50 oC.
(Effective from 2nd step)
Manual hold when dHLd=0.
|Front Panel LEDs||To display the status of control output, Alarms and Ramp/Soak status|
|Memory Backup||Retention of PID and set values in the non-volatile memory in the event of power failure and auto resumption of heating cycle.|
|Alarm Outputs||High or Low or End of Profile Alarm Relays (OUT2 and OUT3)
(contacts rated for 5A @ 230VAC).
|Supply||90-240VAC ( approx. 5VA), 50/60Hz.|
|Size||96 x 96 x 120 mm|
|Panel cut out||92 x 92 mm +/- 0.5 mm|
|Enclosure||ABS plastic enclosure with ABS bazzel and polycarbonate front.|
|A0||User selectable K,R,S,B,||As below|
|A1||K type : Cr/Al thermocouple||0 to 1372|
|A2||R type : Pt/PtRh13% thermocouple||0 to 1768|
|A3||S type : Pt/PtRh10% - thermocouple||0 to 1768|
|A4||B type : Pt30%Rh/Pt6%Rh thermocouple||200 to 1820|
|A5||RTD : (Pt-100)/ 2 or 3 wire||0.0 to 400.0|
|Sr. No.||Specifications||Part No.|
|1||Input from R, S, B t/c with (SSR + 0-5V or (4-20)mA) control output + High or Low and End of Profile Relay outputs. |
For High Temperature Furnace control (up to 1700 °C).
|2||Input from K t/c with only SSR control output + High or Low and End of Profile Relay outputs. |
For Medium Temperature furnace control (up to 1200 °C).
|3||Input from K t/c with (SSR + 0-5V or (4-20)mA) control output + High or Low and End of Profile Relay outputs. |
For Medium Temperature furnace control (up to 1200 °C).
|4||Input from RTD(Pt-100) with (SSR + 0-5V or (4-20)mA) control output + High or Low and End of Profile Relay outputs. |
For Low Temperature ovens (up to 400 °C).