A number of products are available today for three-phase power measurement. Most are complete stand-alone systems with advanced reporting functions. Although these devices typically are configurable, they are functionally limited to power measurement. If you need to interface these devices to a PC or controller, additional networking usually is needed, as well as separate power feeds and mounting requirements.
Given the high price of a power measurement system itself, these additional considerations make implementation an expensive proposition.
“Rather than a stand-alone power measurement system, the power measuring device should be a component of a remote I/O or distributed control system,” says Mark DeCramer, product manager, Wago-I/O-System. “This would remove the burdens of special mountings, power feeds and networking. The device would provide connectivity to all supported I/O networks, due to the nature of the I/O system. Since the device now could be internally powered and configured as part of the I/O system, a lot of complexity could be eliminated, reducing the cost of both the device and its application.”
Wago says its new 750-493 module is precisely that device. “It provides low-cost, three-phase power measurement of an electrical supply network, while allowing maximum flexibility and connectivity as a component of the Wago-I/O-System,” says DeCramer. “Because the DIN-rail mountable 750-493 was designed as an I/O system component, much of the complexity associated with traditional modules has been minimized. There is no need for those added costs related to stand-alone modules.”
The module measures the electrical characteristics of a three-phase supply network, including voltage, current and the calculated effective power, energy consumption and power factor. Connected to a Wago buscoupler or controller, says DeCramer, the module offers a low-cost distributed I/O solution for a comprehensive network analysis via 16 network protocols, including Ethernet, Profibus, Modbus and DeviceNet, and the 300+ digital, analog and special function modules found in the Wago-I/O-System. “At 12-mm wide, the high-density, six-channel 750-493 represents a cost- and space-effective solution to power-system-supply management,” adds DeCramer.
The six-channel power-measurement module dedicates three channels to voltage input and three channels to current input, and is available in 1A and 5A variations to support standard current transformer signal levels. “The intelligent module directly measures voltage, current, energy consumption and power factor [cosf] to calculate effective power and track energy consumption rates,” says DeCramer. “The data provided by this module can be used to ensure economical operation and equipment safety. When one or more 750-493 modules are connected to a Wago controller, the solution can be programmed with Wago-I/O-PRO CAA for data logging, time stamping and historical analysis. For example, this data can allow the control system to optimize power supply to a drive/machine, schedule preventive maintenance in the event of excessive energy consumption and detect instant or cumulative loading in motors, initiating a pre-emptive shutdown for equipment protection.”
The 750-493 has four status LEDs indicating under-voltage conditions for each of the three phases, as well as module status. “As with Wago-I/O-System modules, the termination points in the 750-493 use Cage Clamp wiring technology for fast, easy and maintenance-free wiring,” concludes DeCramer. “For convenience, it also features WSB-Markers for individually labeling termination points.”