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 accomodate 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
Crusher/Grinder/Shredder Motor Interlocks View Details
The performance of size reduction equipment like crushers or grinders can be optimized by controlling the in-feed in order to
Help prevent jamming
Improve the uniformity of the resultant product
Enhance overal t production efficiency
By installing an NK Technologies' Current Transducer or Power Transducer to monitor the infeed to a crushing process, the speed of the in feed drive can be slowed when the crushing motor is working too hard, or the speed can be increased when the crusher is under worked. The analog 4-20 mA proportional signal is fed directly into a VFD, and the drive does the rest of the control.
Additionally, NK Technologies' Current Operated Switches installed on other conveying motors can be used to signal malfunction (for example over-load or motor failure) to help prevent cost equipment damage.
NK technologies current sensors come in a variety of configurations for quick and simple installation either for the OEM or End-User.
Often a band saw is used to cut logs into rough planks, before the planks are processed into finished lumber. Due to inconsistencies in the log (knots, burls and checks), the speed that the log is pulled through the saw must be varied. The operator will often reduce the speed of the cut when smoking occurs, or the blade breaks. By installing an NK Technologies' Current Transducer the operator's job is made easier. By watching the log and a display representing the current draw of the band saw, the operator can achieve a higher rate of output with less down-time.
A similar arrangement can be used with circular saws. The blades become brittle after excessive heating if they are worked too hard. Many automatic systems are in use whereby the currert draw is used to reduce the motor load typicalIy by reducing the feed-rate.
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.
NK Technologies' Current Operated Switches are available in models that will switch at measured currents from just a few milliamps (mA) to over 100 amps. Detecting current flow is the definitive measurement to determine if equiment 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.
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.
