Worldwide, approximately 60% of the electrical power used in factories is consumed by electric motors. All electric motors, regardless of application require electrical current to generate the magnetic fields necessary to create rotation. By measuring this current, useful information can be obtained to monitor the status of the motor and the equipment connected to it. Both AC and DC powered motors are used to drive pumps, fans, conveyors and a broad range of specialized equipment.
Techniques for Determining Motor/Pump conditions
Electric motors utilize current and voltage to operate. The speed of a motor is proportional to the applied voltage and/or frequency, and the torque generated by the motor proportional to the applied current. The combination of the current and voltage (torque and speed) creates the power required to operate. Thus current and voltage measurements may be used to monitor the motor operating conditions and determine motor status. Current and power transducers, as well as current operated switches, provide sensing technology to monitor current and voltage. This aides in determining the condition of an electric motor and provides a signal to direct a specific action. These sensor devices can be used for jam protection, verification of operation, load monitoring, closed loop control, and status alarms. Read more
As we become more aware of occupational health and safety so the need for protection 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.
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.
Spin Pumps are used in the manufacture of synthetic fibers and yarns. Very precise control is required to insure that the product feed rate and the fiber draw rate is matched. It is critical to monitor and protect these spin pumps because they are the heart of the system and are required to run continuously. By installing an NK Technologies’ Current Transducers, the motor current may be monitored providing the control system with key information regarding load. Variations in load may be attributable to a number of factors such as bearing failure, seal failure, suction loss etc. The measurement of load together with other process variables like pressure and flow can provide invaluable information regarding the operation of the vital spin pumps.
Vacuum pumps are used in a variety of applications in the semiconductor industry, heat 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.
An NK Technologies’ Ground Fault Sensor installed on a submersible pump motor provides an 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.
NK Technologies’ Current Transducers are used to monitor motor current and therefore 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
Pumps can become jammed due to foreign matter and cause damage to both the pump and the motor before thermal overloads are tripped. Additionally a blockage in the suction line of the pump can cause the pump to run dry, overheat and break a seal.
By simply installing an NK Technologies’ self-powered Current Operated Switch in one leg of the motor overload (pump jam), underload (suction loss) or underload & overload can be detected quickly before damage occurs.