Convert Reactive Energy from Megavolt-Amperes Reactive Hour (MVARh) to other units

What Is MVARh (Megavolt-Ampere Reactive Hour)?

A Megavolt-Ampere Reactive Hour (MVARh) is a unit of measurement for reactive energy. It is a large-scale unit, equal to one million volt-amperes reactive hour (VARh).

What MVARh Measures: Understanding "Non-Working" Energy

A Megavolt-Ampere Reactive Hour (MVARh) quantifies the total amount of reactive energy consumed or produced over one hour. This is the "non-working" energy required to sustain magnetic fields in inductive equipment like motors and transformers.

While it doesn't contribute to actual work (like heat or motion), its flow is essential for the operation of an AC power system, and utilities track it to ensure grid stability and efficiency.

Why MVARh Matters: Power Factor and Utility Bills

High MVARh consumption is a primary indicator of a low power factor, which signifies an inefficient electrical system. This inefficiency forces utility grids to transport more current than necessary to deliver the same amount of useful energy, leading to increased line losses.

Consequently, many utilities impose a "power factor penalty" or a reactive power charge on commercial and industrial customers' bills. Managing and reducing MVARh is a key strategy for lowering electricity costs.

MVARh vs. MWh: Reactive Energy vs. Real Energy

While often discussed together, MVARh and MWh (Megawatt-Hour) measure two distinct types of energy.

MWh represents real or active energy—the power that performs useful work. In contrast, MVARh represents reactive energy—the power that sustains electromagnetic fields.

Both are components of the total apparent energy (measured in MVAh). Optimizing an electrical system involves minimizing MVARh to ensure that the majority of the supplied energy is productive MWh.

How to Reduce MVARh and Lower Costs

Since high MVARh consumption leads to inefficiency and penalty fees, managing it is a key strategy for lowering electricity costs.

The most common method to reduce reactive power is called power factor correction. This typically involves installing capacitor banks at your facility, which act as a local source of reactive energy, reducing the amount you need to draw from the utility grid.

A Simple Analogy: The Beer Mug

A helpful way to understand these concepts is the "beer mug analogy."

• Real Power (MWh): This is the beer itself. It's the useful part you actually want.
• Reactive Power (MVARh): This is the foam. It's not useful, but it's a necessary part of the total volume in the mug.
• Apparent Power (MVAh): This is the entire mug (beer + foam).

A low power factor means your mug has too much foam (MVARh) and not enough beer (MWh). You're paying for a full mug but getting less of the useful product. Power factor correction is like adjusting the tap to get more beer and less foam in your mug.