What You Need to Know about Power Quality
Power quality refers to the degree to which the electrical network or grid provides “clean” and stable power to your business. Good electric power quality provides a steady voltage supply where the frequency of the supply conforms to a pure sinusoidal waveform.
Think about it like listening to your radio. Poor power quality is similar to staticky poor reception when the station is not tuned in precisely.
Virtually any business is subject to power quality issues. Any buildings containing electronics with power supplies are at risk. This includes industrial facilities, office buildings, water treatment plants, schools, and hospitals, to name a few.
Why is power quality important?
Poor power quality leads to all kinds of problems in your facility. It can reduce the speed of production and damage sensitive equipment, resulting in higher maintenance costs, equipment replacement, and lower operating efficiency. Bad power quality also increases energy consumption which directly increases costs. Good power quality will help your business save money and energy.
How to recognize poor power quality
If you’re experiencing any of the following, your business is likely suffering from poor power quality:
- Regularly replacing motors, variable frequency drives, and other control equipment
- Computer freezes
- Equipment failure
- Voltage surges or sags
- Noisy electrical equipment
- Flickering lights
- A charge for a low power factor on your utility bill
Utility companies typically charge a penalty to customers with a power factor below a specific limit (typically between 0.90 and 0.95). Power factor is a measure of the efficiency of using power in your electrical system.
What causes electrical disturbances in the power system?
Causes can be internal or external to your facility or both.
External causes can be disturbances in your incoming voltage caused by:
- Utility switching on the grid
- Lightning strikes
- Neighboring industrial plants
Only about a third of power problems come from outside your facility.
Internal causes can be:
- Equipment within your facility cycling on or off
- Motors within your facility turned on without sequencing in stages
- Circuit overloads
- Improper wiring
- Harmonics (caused by equipment power supplies)
The great majority of problems experienced within a facility are from motors or other inductive loads as they switch on and off. Examples include HVAC equipment, elevator motors, and robotic equipment–basically, all inductive loads, regardless of size. In the office, things like coffee makers, air conditioners, photocopiers, laser printers, and vending machines can cause problems.
Whether the cause is internal or external, “dirty power” wastes energy and damages equipment.
What to do about “dirty power”
First, it’s essential to find the root causes of the power quality problem.
To identify root causes, it’s wise to engage a reliability specialist to assess the electrical distribution system in your facility. In some cases, utility power can be at fault, and in others, equipment or system issues within your building may cause the problem. The specialist uses power analysis equipment to identify the anomalies in your systems and equipment and provide a detailed strategy for taking corrective measures to prevent costly failures and shutdowns.
A power quality audit differs from an energy audit, both of which are important to managing energy and energy costs in your business. Energy audits assess how much energy your facility and its equipment are consuming. These audits identify the kilowatts (energy consumed at any point in time) and kilowatt-hours (energy consumed over time) used in your business. An energy audit provides a baseline for consumption and helps identify opportunities for reducing energy consumption.
In contrast, a power quality audit focuses on the condition of the electricity flowing through the building’s electrical distribution system as it is consumed. The audit measures how equipment such as computers, LED lighting, high-efficiency variable frequency drives, and control motors are affecting the performance of the power distribution system.
In many cases, the power supplies in these devices create harmonics. Harmonics are currents that can overload wiring to generate heat and possibly fire and can distort the sine waves of the power moving through the system. This “dirty power” causes heating on circuits, failure of motors, and/or failures of drives.
Remedies may include physical devices such as surge arrestors and voltage regulators. Software applications are available to “clean up” the power sine wave.
An investment in your facility’s power quality is a direct investment in your business. Cleaning up the power entering your building and/or its equipment protects the investment you’ve already made in your business’s physical infrastructure. Include a power quality assessment as part of your energy management strategy, as energy management is a money-saving consideration for any business.