PID temperature controller for paint booth heater
Find out how to control the cascade temperature of a spray booth
PID Controller 1650
With the PID 1650 controller you can work with the cascade temperature stability of a spray booth oven (+/- 0.5 °C) with 16 different temperature profiles that allow you to define drying cycles via LCD display.
Overview
- Application criticality: stability and accuracy of the controlled temperature within +/-0.5 °C (+/-32.9°F)
- 1650 controller: Precise dual loop PID cascade controller along with the capability of profile programming. Webserver function to monitor process parameters remotely through mobile, tablet, PC etc.
- Results: +/- 0.5 °C temperature stability over the drying cycles
The process
For high quality finishing in painting process of luxury cars and industrial components, the drying process require precise accuracy and temperature stability.
The dryer should work in a range between 40°C and 85°C (104°F/185°F). There are specific temperature cycles according to the chemical characteristics of the coating material.
The typical program cycle consists of 3 phases:
painting, drying and cooling.
The drying process could have different source of heat, for example gas combustion, diathermic oil or electric duct heaters, IR lamps etc.
The challenge
In this specific case the heating element consists of a battery of 3 legs electric heaters combined with a forced air ventilation system to enable the temperature uniformity in the dryer.
Control system
Scope of the control system is to perform +/- 0.5°C (+/-32.9°F) stability of the temperature during the drying process.
Controller shall have the capability to define PID algorithm factoring delta between air temperature of the heaters and the one in the oven. Absence of this could cause temperature instability in the dryer affecting the quality of the finishing product.
A set of drying temperature profiles (recipes) are required to meet different finishing treatment.
Power controller
The electric heater coil is three legs load with a single-phase control. Product and system diagnostics to be provided in the event of partial or full heater break or short circuit conditions.
Product benefits
1650 controller
- Precise dual PID loop controller: accuracy 0.1%
- Control features: ratio, cascade, variable set point program
- Configurable analogue Input signal : TC, V, mA, RTD
- Configurable output signal: V, m A, valve control
- Logic and math function blocks, real time clock, totalizer, timer
- Wide and bright LCD display for prominent visibility of operators
- Web server to enable remote service
- Modbus TCP communication protocol for third party equipment connectivity
GTF power controller
- GTF single phase power controller
- Up to 250 A 400 Vac.
- Control mode: Phase angle, zero crossing, soft start
- Fault alarm: heater break diagnostics
- Connectivity: Modbus RTU
Solution
Control Scheme
The 1650 Dual loop controller meets the requirement for a precise and stable control of the cabin temperature, performing different temperature profiles (recipes) while driving a 3 phase (legs) resistive load.
As per (Fig. 1), the PID1 act as master controller of the cabin temperature, the output signal is the set point for the PID2 of the air heater temperature.
The 4-20 mA output to drive single phase Power controllers. model GTF
The cascade control algorithm to compensate the different thermal dynamics of the temperature value of the resistive duct and the ones in the cabin.
The cabin temperature maximum error +/- 0.5°C (+/- 32.9°F)
SP programmer (ramp & soak)
Up to 16 different temperature profiles have been stored and recalled via PLC, front instrument or manual selector.
The graphical display provides messages (Fig. 3) and instruction to help the operator in the interaction with the plant.
Energy totalizer
Partial and absolute totalizer is available for measuring the energy transferred to the heating system.
Remote access
Web server connectivity (Fig. 2) to enable remote access to the controller for diagnostics and control process parameters, using devices such as PCs, tablets, mobile phones etc.
Power Control
The three GTF Series Power Controllers drive the individual phases of the three-phase powered electric heater.
- Diagnostics with alarm signal in case of partial load failure HB (Fig. 4)
- Self-learning alarm threshold for HB alarm intervention
- Integrated reading of the impedance, current, voltage, frequency and load power values
Connectivity: Mod bus TCP/IP
