Current Loop Web Controllers
Last Updated: April 1, 2025
Description
Current Loop Web Controllers are devices used to regulate various parameters in web processes, such as tension, rate, or alignment. They receive inputs from sensors, perform control functions, and output control signals to maintain the desired state of the web process.
Working Principle
Current Loop Web Controllers operate by using control loops to maintain the desired process conditions. They utilize various control strategies, including proportional, integral, and derivative (PID) control, to adjust the output based on the difference between the desired setpoint and the actual process variable. The use of current loops, such as 4-20 mA, ensures consistent signal transmission over long distances, as current remains constant throughout the loop, unaffected by voltage drops.
Applications
Current Loop Web Controllers are commonly used in industrial settings where precise control of web processes is required. Specific examples include controlling the tension in paper manufacturing, regulating the alignment in textile production, and maintaining the rate of material feed in packaging lines.
Advantages over other Web Controllers
One significant advantage of Current Loop Web Controllers is their ability to maintain consistent current levels across all devices in the loop, even over long distances. This ensures reliable signal transmission and reduces the impact of voltage drops, which can be a limitation in voltage-based systems. Additionally, the use of PID control allows for precise adjustments, improving the accuracy and stability of the control process.
Limitations
A limitation of Current Loop Web Controllers is the potential for voltage losses and attenuation due to conductors and connected devices. While these do not affect the current, they can impact the overall system performance if not properly managed. Additionally, the complexity of setting up and tuning PID parameters can be a challenge, requiring skilled personnel for optimal performance.
Considerations
When considering the implementation of Current Loop Web Controllers, it is important to evaluate initial costs, which can vary based on the complexity of the system and the number of control loops required. Operating expenses may include energy consumption and maintenance costs, which can be minimized through efficient design and regular upkeep. Durability and accuracy are critical factors, as these controllers must withstand industrial environments while maintaining precise control. Replacement and maintenance costs should also be considered, as regular calibration and potential component replacements are necessary to ensure long-term reliability.
from ABB Measurement & Analytics
MC 400 covers most mechanical arrangements. This means the user only has to follow the step-by-step instructions in order to set up the controller and to have a correct strip tension calculated. Predefined standard measurement modes. Prepared to calculate true strip tension from all mechanical... [See More]
- Control Signal: Analog Voltage Output; Current Loop Output; Switched Output; Pulse / Frequency; Serial / Digital; Network / Fieldbus Output
- Features: PLC
- Control: Limit; Linear; PID
- Form Factor: Chassis
from Dover Flexo Electronics, Inc.
Its stable output and versatility in managing web tension in the most challenging applications are unmatched. The SteadyWeb6 maintains a pre-selected tension set point on a web machine or press by measuring web tension from a tension transducer (or transducer pair), and then sending a compensating... [See More]
- Control Signal: Analog Voltage Output; Current Loop Output
- Form Factor: Chassis; Wall-Mount Full Enclosure
- Features: Rate Indication/ Control
- Interface: Digital Front Panel
from FMS USA, Inc.
The CMGZ309 tension controller responses to a broad range of missions. Its field of application is in production lines where moving web products are manufactured, processed or finished. As a plug & play unit a minimum of tuning tasks are required. Functions can be configured very easily via a... [See More]
- Control Signal: Analog Voltage Output; Current Loop Output; Switched Output
- Form Factor: Chassis; DIN
- Control: PID
- Interface: Digital Front Panel
from Dover Flexo Electronics, Inc.
The EasyViewTM Tension Indicator is a small, general-purpose device for the measurement and display of process web tension. Using Quik-CalTM digital technology, the unit is zeroed and calibrated simply using push buttons. In addition to amplifying the signal output from tension transducers installed... [See More]
- Control Signal: Analog Voltage Output; Current Loop Output
- Form Factor: Chassis; DIN; Wall-Mount Full Enclosure
- Features: Rate Indication/ Control
- Interface: Digital Front Panel (optional feature)
from FMS USA, Inc.
The CMGZ600 series controller integrates many functions into one compact housing. It offers selectable control of unwind brake or drive, intermediate drive, or winding drive. The CMGZ600 series controller is available in a 2 channel version offering 2 independent closed loops for tension control of... [See More]
- Control Signal: Analog Voltage Output; Current Loop Output
- Form Factor: Chassis
- Features: PLC
- Interface: Digital Front Panel
from Dover Flexo Electronics, Inc.
The EasyWeb ™ is an open loop torque controller designed to maintain constant web tension or provide taper tension to center driven rewind or unwind applications. Web tension is regulated by controlling motor or brake torque based on varying levels of roll diameter. An Inertia compensation... [See More]
- Control Signal: Analog Voltage Output; Current Loop Output
- Form Factor: Chassis; Wall-Mount Full Enclosure
- Features: Rate Indication/ Control
- Interface: Switches; Digital Front Panel
from Dover Flexo Electronics, Inc.
The TriView Left-Right-Total tension indicator displays web tension on a large, bright LCD touch screen. Total tension is continuously displayed digitally and on a simulated analog scale readout. By tapping the touch screen a machine operator can select either left and right tension readings below... [See More]
- Control Signal: Analog Voltage Output; Current Loop Output
- Form Factor: Wall-Mount Full Enclosure
- Features: Rate Indication/ Control
- Web: Tension Indication/ Control
from Dover Flexo Electronics, Inc.
The TriView Left-Right-Total tension indicator displays web tension on a large, bright LCD touch screen. Total tension is continuously displayed digitally and on a simulated analog scale readout. By tapping the touch screen a machine operator can select either left and right tension readings below... [See More]
- Control Signal: Analog Voltage Output; Current Loop Output
- Form Factor: Chassis
- Features: Rate Indication/ Control
- Web: Tension Indication/ Control