UV & IR Lamp Status Monitoring
Ultraviolet (UV) lamps are used commonly to disinfect water by killing bacteria. High Intensity Infra Red (IR) lamps are used in a variety of industrial processes to provide heat both for drying and curing processes. Correct operation is very important and can be determined by measuring current draw. Using an NK Technologies’ Current Operated Switch provides simple and quick verification. The on/off contacts of the switch may be used to simply indicate status to an operator using a lamp or wired to the input of a PLC preprogrammed with the necessary corrective action. Alternatively, NK’s Current Transducers may be used to provide an accurate measurement of the current draw by a UV, IR or other light source.
Critical Lighting Systems Preventative Maintenance
High technology lamps have been developed for a variety of specialized industrial and commercial applications. These lamps are expensive and their useful life should be maximized. Installing an NK Technologies’ Current Transducer to measure the current draw of a lamp provides the information to determine the lamp’s condition by comparison to known characteristics. Intelligent control devices, like PLCs, are programmed to adjust the applied voltage or current to optimize the life of the lamp.
Industrial electrical heaters are prone to ground leakage due to the breakdown or contamination of insulators. The use of NK Technologies’ Ground Fault Sensors enables early detection of leakage Currents as small as 5mA. The on/off output of the sensor can be used to trigger a circuit interruption device (for example a shunt-trip breaker) or a monitoring device like a PLC to determine the required action. Latching and auto-reset models are available in both normally energized and normally de-energized configurations suitable for most applications.
Heater Life Prediction
As an electric heating element ages, its resistance also changes. Many high technology and extreme temperature applications employ exotic and expensive elements. Where the value of the products or materials being heated is high, the failure of a heater or heating element has a financial impact resulting from either reduced quality or scrapped materials. By measuring the current drawn by the element using an NK Technologies’ Current Transducer the resistance of the element can be determined and compared against a known ageing characteristic. When the element reaches a predetermined state it can be replaced prior to failure i.e. predictive maintenance. NK Technologies’ Current Transducers are used in conjunction with intelligent PLC systems when high power SCRs (also known as thyristors) or triacs are installed.
The auxiliary contacts in a motor starter are commonly used to indicate when the motor is running. However, auxiliary contacts only indicate the position of the contactor, not the actual load status. If a downstream disconnect is open (for example, for maintenance) or the contact fails (either sticks or dirt build-up) there can be serious consequences.
At a large fish farm, failed aerator pumps resulted in massive stock losses. Because the auxiliary contacts remained closed when the pump failed, the alarm was never activated, the back-up pumps were not switched on and the fish suffocated due to lack of oxygen. Now NK Technologies’ Current Operated Switches have been installed to provide an alarm signal and a signal to automatically switch over to the back-up aerator pumps.
Closed Loop Control
Normal linear AC induction motors have a current characteristic that increases with load. Thus a measurement of current is proportional to the motor load. NK Technologies’ True RMS Current Transducers are designed to work in conjunction with variable frequency drives (VFD) and measure the current in the leg of the motor.
At an engine block manufacturing facility NK Technologies’ Current Transducers provide the input to a PLC used to position the rotating wire brushes in order to clean away burrs and debris after machining. As the current, and thus the load, changes so the brushes are positioned for optimal clean-up. Similarly Power Transducers are used to control the position of wheel wash brushes in a carwash. Power measurement provides a more linear relationship for motors and other loads with non-linear current characteristics. Current Operated Switches are used to co-ordinate operations between conveyor, washing and drying systems.
DC Motor Installations
Many applications requiring high torque at low speeds, like bridge cranes and log carriages, use DC shunt wound motors. Since it is relatively easy to control the speed of a DC motor by adjusting the voltage to the field windings, precise regulation is afforded to applications like printing press paper feeds or web control of multiple motors in the paper making process. Using an NK Technologies’ DC Current Transducer will provide an analog signal that can be used to keep the motor from over-current situations. Using an NK Technologies’ DC Current Operated Switch will insure that if the motor field supply is lost, the motor will not over-speed to the point of self-destruction.
Conveyor Jam Protection
When conveyors jam and the drive motor continues to run, expensive mechanical damage to the drive components often occurs. By installing an NK Technologies’ Current Operated Switch an overload condition, detected by higher than normal running amps, can be used to switch off power to the motor before mechanical damage results. The switch setting can be adjusted so it is not affected by normal changes in conveyor load. Current operated switches are the modern day equivalent of less reliable electromechanical jam relays that have been in use for many decades.
In situations where there may be large variations in load an NK Technologies’ Current Transducer may be used to feed motor amps to the conveyor control system, commonly a PLC. The PLC may be programmed to accommodate different setpoints for different mechanical loads so that jam protection is provided from light to heavy loads. In situations where the conveyor is not able to accept analog signals NK Technologies has developed a patented transducer with a frequency output suitable for the Digital Inputs of most PLCs.