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.

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.

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.

UV & IR Lamp Status Monitoring

Ultraviolet (UV) lamps are used commonly to disinfect water by killing bacteria.UV & IR Lamp Status Monitoring 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 Preventative Maintenance of a Critical Lighting Systemindustrial 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.

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.

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