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.

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.

Equipment Ground Fault Monitoring

As we become more aware of occupational health and safety so the need for Equipment Ground Fault Monitoringprotection against ground faults is growing. Industrial electrical equipment is fed via a distribution system which in turn is connected to a main feed. Ground fault protection may be installed, for instance at a main breaker, protecting the branch circuit but not necessarily a valuable or critical piece of equipment. Industrial Ground Fault Sensors from NK Technologies are designed to be installed in individual pieces of equipment or their electrical feed. The sensors provide an on/off output that may be used to operate a circuit interruption device like a shunt trip breaker or feed into an alarm system. With over 100 models to choose from, there’s sure to be one to fit your application.

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.

Current Transformer Monitoring

C.T.s (Current Transformers) have been used for many years to measure AC Current Transformer Monitoringamperage. There are many C.T.s installed throughout Electric Utilities, Process Plants and Manufacturing facilities. Typically a C.T. provides either a 1A, or more commonly a 5 Amp AC output on the secondary side. In order to use this signal for a modern control system (DCS, PLC or DDC) or Data Logging System a signal conversion or conditioner device is required to provide an analog DC signal.

C.T.s step down current and the secondary has to feed into a very low impedance to maintain accuracy. In the event that the secondary is open-circuited during operation the device operates as a step-up voltage transformer since there is nowhere for the current to flow and voltages of several kV appear on the secondary, overheating occurs and combustion or explosion often results. NK Technologies’ Split-Core Current Transducers are simply and safely snapped over the shorted secondary of a C.T. to provide a fully isolated analog 4-20mA DC signal proportional to the current in the secondary, which in turn is proportional to the measured (primary) current.

NK’s Split-core Current Transducers are used to safely monitor the secondary of high voltage C.T.s used in power generation and distribution in the low voltage cubicles.

Insulation Breakdown

Industrial electrical heaters are prone to ground leakage due to the breakdown orInsulation Breakdown 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 Heater Life Predictiontechnology 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.

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.

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