The Parr Model 4871 Process Controller has been developed to provide an integrated stand alone control system for controlling either a single reactor with multiple feed and product controls or multiple reactors operating independently or in parallel. The 4871 is the ideal choice for all of Parr Instrument Company’s custom systems, including: tubular reactors, multiple reactor systems (both batch and cascade systems), continuous flow stirred reactors, and fluidized bed reactors.
The Parr 4871 Process Controller combines the following components into a single control system:
- Honeywell HC900 Hybrid Controller.
Flexible, Powerful Software:
- SpecView SCADA software.
- System set up with graphical user interface configured to individual requirements.
- 4875 or 4876 Power Controllers for handling heating, cooling, safety and motor control devices.
I. Control Module
The control module of the Parr 4871 Process Controller is a Honeywell HC900 Hybrid Controller. This controller combines analog and logic control into a versatile, cost-effective controller designed specifically for process applications requiring analog measurement combined with programmable control actions.
|Analog Input (AI) Maximum Channels||480|
|Analog Output (AO) Maximum Channels||200|
|Digital I/O Maximum Channels||1920|
|Control Loops||Per Memory|
|Logic Scan||25-50 ms|
|Loop Scan||500 ms|
|Peer to Peer Communications||Yes|
Input / Output
The controller is adapted to each user’s requirements by adding to the control chassis input and output modules. Each module provides for between four and sixteen individual inputs or outputs fully isolated from one another. These modules include:
Input Modules: The analog inputs are of universal type and are most commonly used for thermocouple or RTD temperature sensors, strain gage type pressure transducers, and similar devices with mV, V, or resistance inputs. Input isolation, cold junction compensation, and burnout protection are incorporated into the circuitry. Each analog input module provides for eight separate inputs.
The digital inputs can be logic inputs or contact closures. These are typically used for sensing valve positions or conditions of safety devices. Each digital input module provides for sixteen separate inputs.
Output Modules: The analog outputs are 0-20 mA. A suitable dropping resistor can be used to convert this to 0-5 or 0-10 VDC. Analog outputs are commonly used to set stirrer motor operating speeds, position control valves, or drive mass flow controllers or pumps. Each analog output module is capable of controlling four separate devices or functions.
The digital outputs are open collector type capable of sinking up to 300 mA. They are commonly used to control heaters, solenoid valves for cooling or other flow control, system safety shut down, visual and/or audible alarms, and similar devices. Each digital output module is capable of controlling sixteen separate devices or functions.
The controller can provide any number PID or ON/OFF control loops, limited solely by the available CPU memory.
The PID control algorithm includes auto-tuning and fuzzy logic overshoot suppression for each control loop. For heating and cooling control, the PID control loops provide time proportioning of the associated digital output.
Many temperature control applications utilize two separate time proportioning outputs with one PID controller; one for heating and one for cooling.
Control loops can be linked together to provide cascade, feed forward or ratio control for difficult or advanced control applications. Both high and low limit values can be entered for each control loop to sound alarms or initiate safety control schemes.
Set Point Programming
Ramp/Soak profiles for controlling the entire process of a reactor can be written using the set point profiler incorporated into the control firmware. A single profile may be from 2 to 50 segments in length.
A typical profile might be a ramp and soak of the reactor temperature but, in addition, the analog and digital outputs can be tied to the basic profile to start and stop flows, activate stirrers or accessories, or change alarms. Any of the set points within the profile can be protected with the set point guarantee function that assures that the process variable will be within the entered limits before the profile can proceed.
The number of set point profiles is limited by the amount of available memory in the controller CPU. Typically, at least eight separate profiles can be running simultaneously. For example, eight reactors can be running a unique program at the same time.
While a maximum of 99 profiles can be stored in the controller itself, an unlimited number can be stored in the operator’s PC for rapid transfer to the controller.
In addition to the set point profiling capability, the controller is also equipped with a set point scheduling function. This feature can operate up to 8 profiles operating on a common time base.
The 4871 Controller includes Operational Sequence Control
The sequence control function offered by the 4871 Controller greatly expands the capabilities of this control for users who wish to control reactor systems. The operation of valves, pumps and other peripheral devices can be programmed on either a time or an event driven basis. Sequences can be very simple timed events or they can be very complex with multiple nested default sequences programmed to occur only if process feedback indicates a need to take alternative actions.
Each 4871 Controller is equipped with an RS-485 and Ethernet communication ports. The RS-485 port is used for initial configuration and communications setup. The Ethernet port provides communication with the host PC when using the SpecView GUI program. Multiple controllers, each with a unique address, can be networked on the Ethernet interface with a single connection to the PC.
The principal advantage of the Ethernet interface is that it allows the user to use an existing network infrastructure to connect the controller to the PC. As a result, one can operate the controller over the network from anywhere within your facility. Additionally, internet access from remote locations becomes possible. This type of connectivity offers unique possibilities, for example, related to remote diagnostics and system troubleshooting.
Three Models Available
Parr 4871 Process Controllers are available in three different models to cover a wide range of applications. The 4871A will accept four I/O modules (typically up to 36 inputs and outputs). The 4871B will accept up to eight I/O modules and the 4871C will accept up to twelve I/O modules. If more than 100 inputs and outputs are required, multiple controllers can be linked.
|Model||Width, in.||Height, in.||Depth, in.|
II. Operator Interface
SpecView SCADA Software
SpecView describes their product as “Software for people with other jobs”. That seems to be an excellent description of this software package used with the 4871
- Interface with the control package
- Develop the graphical screen layout
- Establish the data logging profiles
- Prepare custom reports
- Create bar graphs
- Generate time trend graphs
- Monitor alarms
- Create flexible recipes
- Retrieve and replace logged data
- Operate the reactor system(s)
The full software package, not just a run-time version, is supplied with 4871 Controller so operators can enhance their system as their needs change or expand/change their applications. Download a demo at www.specview.com.
Graphical User Interface
An integral part of the Honeywell Controller is the hybrid control designer software. This is the “Drag and Drop” software that enables Parr to rapidly establish the controller’s internal logic and adapt it to individual systems requirements.
The user can employ this same software to change or enhance the fundamental logic of the controller as additional components are added to the system or as functions need to change.
Current Industrial Standards
Modbus, Ethernet, auto-tuning, fuzzy logic, auto-configuring Man Machine Interface (MMI), supervisory control and data acquisition (SCADA), multi-loop control; these are a few of the terms and capabilities designed into the hardware and software incorporated into the Parr 4871 controller.
This modern and powerful package enables Parr to configure and build turnkey systems within weeks of order at very attractive prices.
In most laboratory and pilot plant applications, a PC will be used for the operator interface. A touch screen interface is also available. For plant or production applications, an industrial type user interface box with a color graphic LCD is available.
The PC used with the 4871 serves several functions. It is the operator’s user interface for controlling the process. It also logs all of the operating data generated during a process run. It can also store multiple setups for rapid transfer to the 4871 Process CPU.
Any modern PC with current Windows operating system can be used with these controllers.
It is important to note that the control of the process always resides within the 4871 Controller, and not in the PC itself.
III. Power Controllers
Parr designs, builds and furnishes power controllers to adapt the analog and digital outputs from the 4871 Controllers to the reactors or systems being controlled. These power controllers handle all of the high current power circuits so that the control circuitry is isolated from these loads. This also makes it possible to install the controller in a control room some distance from the system being controlled.
4875 Power Controller
The power controller(s) will be designed for each individual system, but as an example, a 4875 power controller includes:
- A solid-state relay sized to handle the current drawn by the vessel heater. This is commonly a 25-amp relay with its protective fuses.
- A solid-state relay sized to drive a solenoid valve to control the flow of cooling water to the vessel.
- A motor speed controller that converts the analog output signal from the controller to the electrical signal required to drive the specific stirrer motor. A circuit breaker for the motor is also provided.
- A lockout relay to shut down the heater circuit should an alarm condition be detected.
- Status lights for the principal functions.
- Connections of appropriate style for the power input and device outputs.
|Model||Width, in.||Height, in.||Depth, in.|
Note: One model 4875 Power controller is required for each reactor in a parallel system.
4876 Power Controller
The 4876 power controller is equipped with three solid state relays, three lockout relays, and a single motor control. It is used with the 4871 to control up to three separate heaters and one motor. It can only be used in 230v systems.
4876A Power Controller
The 4876A Power Controller is the same as the 4876 described above but without motor control capability.
|Model||Width, in.||Height, in.||Depth, in.|
IV. System set up with graphical user interface
Current Industrial Standards
Modbus, Ethernet, auto-tuning, fuzzy logic, auto-configuring man machine interface (MMI), supervisory control and data acquisition (SCADA), multi-loop control; these are a few of the terms and capabilities designed into the hardware and software incorporated into the Parr 4871 controller. This is a very modern and powerful package that enables us to offer turnkey systems ready to run within weeks of order at very attractive prices compared with custom programmed systems previously available.
V. 4871 Controller for use with Series 5000 Multiple Reactor System
The photo to the right illustrates a six station multi-reactor system. Each reactor is equipped with it’s own constant pressure gas delivery system. The 4871 Controller maintains all of the important system parameters, including temperature and stirring speed, and records the gas consumption of each of the reactors.The 4871 Controller provides two options for controlling the temperature Ramp and Soak programming of the individual reactors.
1. Set Point Scheduler
Using the Set Point Scheduler, different temperature profiles could be programmed for each reactor, but the length of time for each segment of the profile was fixed for all reactors. For example, each reactor could be heated to an individual temperature set point, but the time allowed to reach this set point was the same for all reactors as would be the time they were held at this set point.
2. Set Point Programmer
Using the Set Point Programmer, completely independent temperature profiles could be established which vary not only in the set point, but also in the length of the segment. The 4871 Controller includes Operational Sequence Control
The sequence control function offered by the 4871 Controller greatly expands the capabilities of this control for users who wish to control reactor systems. The operation of valves, pumps and meters can be programmed on either a time or an event basis. Sequences can be very simple timed events or they can be very complex with multiple nested default sequences programmed to occur only if process feedback indicates a need to take alternative actions.