I'm trying to figure out how to measure energy consumption with a power meter.
It reports for the three phases:
- Total Active Energy
- Forward Active Energy
- Reverse Active Energy
- Total Reactive Energy
- Forward Reactive Energy
- Reverse Reactive Energy
Where:
Total Energy = Forward – Reverse, for both Active and Reactive versions.
The question is what is Forward Reactive Power and Backward Reactive Power?
My understanding is that reactive power is casued by inductive elements in the machines, causing a "backward" flow (from machine to generator).
What is then the Reverse Reactive power?
If I'm interested to find out my energy bill cost then (if I understand correctly):
- for residential consumers: I should look at total active energy
- for industrial consumers: it varies, but sometimes also the reactive part is billed. Would this be the total reactive?
Thank you! I'm not an engineer, apologies if the question is nonsensical.
Best Answer
Worldwide, every supplier has their own billing scheme. In some places or at some time in the future, residential consumers may be concerned with reactive energy. Today few if any consumers should be concerned with reactive energy. Net energy seems to be the most-used term for forward or positive energy, energy going to the consumer minus reverse or negative energy supplied by the consumer. Consumers who supply energy from their own generation or storage may be concerned only with net energy, but they may also need to consider forward and reverse energy separately. Suppliers may (1) simply bill for forward net energy, (2) bill for forward energy and give partial credit for reverse energy, (3) give credit for reverse energy but carry net credit to the next billing period, (4) pay the consumer for net reverse energy, (5) base the billing policy on the time of day, (6) do something else.
Net reactive energy is always zero. Reactive energy supplied during one half-cycle of the waveform is returned during the next half-cycle. The charge is often called a power factor penalty or a demand charge. The charge is often based on the minimum power factor during a given time period or the maximum current during a given time period. I don't have any further details of example billing strategies.