High Performance Current Sensing for Automation Applications
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Safety Interlocks

NK Technologies’ Current Operated Switches are available in models that will Safety Interlocksswitch at measured currents from just a few milliamps (mA) to over 100 amps. Detecting current flow is the definitive measurement to determine if equipment is on or off, a motor is running or not, a heater is on or off etc. NK’s Current Switch products are installed for interlocking for operational and safety purposes.

Welder Tip Dressing

Motor-driven tip dressers are used in conjunction with robotic resistance Welder Tip Dressingwelders in a manufacturing area like an automobile body assembly plant. Essentially they are like large pencil sharpeners and they require regular maintenance. After maintenance the dressers are not always switched back on, so that when the robotic welder requests tip sharpening, the tips are not dressed and poor quality welds result, which in turn produces poor quality panels. By installing an NK Technologies’ Current Operated Switch on the tip dresser the status is signaled and an alarm is generated to warn if the dresser remains un-powered and offline. NK’s unique split-core packaging is ideal for retrofit installation and the compact solid-core unit is well suited for OEM applications.

Isolated Alarm System Interfacing

If an alarm or monitoring system is to be installed adjacent to another, (for Isolated Alarm System Interfacingexample: a municipal hurricane or tornado warning system) it is desirable to tie in to it. This can be achieved by the utilization of an NK Technologies’ Current Operated Switch (The split-core version is ideal for this). The switch simply detects current flowing in a conductor to say the audible or visual alarm providing a fully isolated ‘repeater’ signal. Switches are available for both AC and DC applications.

Power Factor Correction Control

With ever increasing demands for electrical power the power generating Power Factor Correction Controlcompanies are beginning to penalize customers with low Power Factors. Low PFs can be considered very inefficient use of electrical energy. A low PF can be corrected by the installation of PF Correction capacitors. Although this can be achieved at the main feeder most facilities, due to multiple varying loads, choose to install PF correction on individual pieces of equipment (like a large motor) or area of plant. When a load is switched off, unless the PF correction capacitors are removed, undesirable over-correction occurs. Sophisticated automatic control systems are available but are very expensive. A simple way to switch a PF correction capacitor bank is to use an NK Technologies’ Current Operated Switch. When the load goes down, for example at night when equipment is not used, the PF correction capacitor is switched out. Then when load returns it is switched back in.

Power Transformer Monitoring

Installing an NK Technologies’ Current Transducer over the conductors on the Power Transfomer Monitoringsecondary of a transformer can be used to alarm if the current draw reaches a critical level. Action can then be taken to reduce the load before the transformer overheats.

Most large power transformers utilize auxiliary cooling fans, drawing cooler air from a distance away from the transformer. NK Technologies’ Current Transducers or Current Operated Switches are used to monitor these fans for overload from bearing failure, under loads from drive component breakage or slippage, and to just be sure that the fan is energized and doing its required job.

Generator Installations

The need for back-up power for critical loads is becoming more and more Generator Installationsapparent to operating and maintenance personnel. Many existing factories and facilities are also adding generators to assist the grid connection supply during times of excessive consumption, or to help the plant ride through periods of peak usage when the utility charges a premium for power. Monitoring the current demand provided from a generator allows for load shedding of non-critical loads when the generator is nearing its capacity. NK Technologies’ Current Operated Switches close when the demand, measured by current, is too high, and by connecting to a controller (like a PLC), less critical loads can be disconnected from the system.

Lamp Failure Detection

The simple addition of an NK Technologies’ Current Operated Switch in a Lamp Failure Detectionlighting circuit provides an isolated on/off signal to either a relay to automatically switch to a back-up lamp or signal a PLC to indicate lamp failure. The split-core model is designed for quick and simple installation for existing installations and the solid-core device provides a compact solution for new installations.

Vacuum Pump Monitor

Vacuum pumps are used in a variety of applications in the semiconductor industry, Vacuum Pump Monitorheat treatment, plastics and packaging industries. By adding an NK Technologies’ Current Transducer over the lead feeding a vacuum pump, it can easily be determined when all the air has been removed from a vessel or envelope. The analog output can signal the vacuum or equipment controller that it is time for the next step in the process. In the case of an automated packaging machine, a drop in current will signal that the package is ready for sealing.

Moisture Ingress on a Submersible Pump Motor

An NK Technologies’ Ground Fault Sensor installed on a submersible pump motor provides Submersible-Pump-Motoran easy to install replacement or addition to moisture sensors housed in the motor casing. Unlike moisture sensors that have to be wired back to the motor control center, the GF sensor is installed in the motor control center. By detecting the ground fault current resulting from moisture ingress or other potentially dangerous condition remedial action can be taken prior to catastrophic failure. Either the pump can be replaced at the next convenient time or switched off and a back-up pump started.

Pump Load Monitoring

NK Technologies’ Current Transducers are used to monitor motor current and Pump Load Monitoringtherefore motor load. The output from the transducer may be fed to an analog or digital indicator or a Programmable Logic Controller (PLC) for more sophisticated monitoring and control.

NK Technologies’ Power Transducers provide load monitoring in more critical applications where the addition of voltage measurement and the determination of the phase relationship between current and voltage (power factor) provides more control.

NK Technologies’ Ground Fault Sensors keep the pumps safe by measuring ground leakage currents as low as 5mA. This also provides an alternative to moisture sensors used with submersible pump motors.

Also see these other articles:
Pump Jam & Suction Loss
Moisture Ingress on a Submersible Pump Motor

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