The APN Series Power Monitor from NK Technologies measures three phases of current and voltage and computes values necessary to track power usage. It uses current transformers to measure the amperes. The line voltage connects directly to the transducer, up to 600 VAC. The result is 14 data points in the RS485 Modbus RTU format.
Electrical energy is measured in watts over time. To measure watts in an alternating current circuit, the supplied voltage is compared with the current, and whether the current peaks before the voltage (leading power factor in a mostly reactive circuit) or the current peaks after the voltage (lagging power factor in a more inductive circuit), the real power is measured.
The APN Series Power Monitor uses electronic smart meters to measure watts, but they only provide information about the entire service consumption. To monitor individual loads or processes, watt transducers or power monitors can be installed. The purpose is to obtain information to help isolate potential problems such as phase loss or voltage sags and voltage spikes, unbalanced current phase to phase, and to help avoid utility surcharges levied for poor power factor.
The APN’s RS485 Modbus RTU format is compatible with many programmable logic controllers and fits seamlessly into industrial communications networks, both hard wired and wireless depending on the specifics of the application. External power improves reliability when used in conditions where power interruptions and voltage sags are common.
The APN Series Power Monitor can be configured to accept 5 amp secondary current transformer inputs or sensors producing 333mVAC proportional to the AC current of the circuit, or they can use factory matched Rogowski coil inputs or the safer ProteCT™ low voltage output CTs. The primary circuit voltage is connected directly to the monitor for 600 VAC or lower, or through a potential transformer for monitoring circuits of higher potentials.
APN Series Power Monitor power sensing applications include: Plant energy management (measure power usage of a single piece of equipment, an area of a plant, or the entire facility), conveyers (detect jam and overloads and check that belt is loaded properly by measuring the power consumption), and pump monitoring (detect dry run from clogged, intake, or discharge line and monitor impeller cavitation and bearing wear).