Fans and pumps use motors and drives. The electricity consumed by motors in buildings is significant. Globally electric motors are responsible for 40% of all electricity consumption [The Carbon Trust, Motors and Drives, 2011].
Operational costs of motors far exceed the initial capital costs; therefore there is the potential for huge savings in energy through efficient use of motor drives.
Oversized motors are inefficient. It is relatively easy to measure the electrical current to the motor and compare this to the rated current.
Incorrectly sized pumps should be sized so that they run at between 50% and 90% of their peak load capacity. Undersized pumps may be running constantly at peak load which is not efficient, while oversized pumps will be running at reduced efficiency (i.e. below 40% rated capacity) all the time.
Monitoring the motor current will enable the load to be estimated relative to the manufacturer’s specification. Information about the installed motor can be found on the manufacturer’s name plate (an example is shown below). This should cover the rated voltage, rated amps, rated power, power factor, mains supply frequency, nominal speed and efficiency class.
Therefore, if the nameplate full-load current is known and the actual current is measured, one can estimate the motor load.
The Electrex monitoring networks are the best solution for similar measurements used in energy auditing and energy efficiency programs. Indeed, with a single system it is possible to control all the energy sources (electrical energy, gas, water, etc.), the environmental parameters related (temperature, humidity, CO2, etc.) and process parameters (compressed air pressure, calories, levels, states, etc.). In addition with the same system it is possible to automate the management of ON/OFF events, automatic adjustments, remote control, alarms, etc.
In the example diagram above, the Yocto net, connected to the Ethernet network, is the system’s gateway (Modbus TCP interface, datalogger and WEB/FTP server) for the:
- X3M 96 H – energy data manager – measuring the energy consumption, the quality of energy and related parameters of the electrical motors, check the alarm states, turn ON/OFF an alarm system in case of threshold exceeding, and through the WEB features of the Yocto net gateway can send a notification e-mail to the people in charge.
- Yocto I-O – input-output device with a built in memory and clock – which logs the data coming from water meters, gas meters, and compressed air.
- RS485 – input-output module – which retrieves the measures from environmental, process and level sensors.