POWER QUALITY

Understanding

Surge Protection Devices (SPDs) solve one specific problem: voltage surges.

Click any tile below to learn about different power quality issues and which solutions address each one. Understanding the difference between surges (transients), undervoltage, harmonics, and other electrical problems helps you choose the right protection equipment.

Normal Operation

Clean Power

Ideal power quality with clean 60Hz sine wave

Normal operation shows a clean sine wave at 60Hz with stable voltage. This is what your electrical system should look like under ideal conditions. No power quality issues present.

Voltage Sag

Brief Voltage Drop

Short-duration reduction in voltage

Voltage sags are brief drops in voltage lasting milliseconds to seconds. Common when large motors start or heavy loads switch on. Different from sustained undervoltage. Equipment may reset or malfunction briefly. SPDs do not address voltage sags.

Power Interruption

Momentary Outage

Brief complete loss of power

Undervoltage

Voltage Sag / Dip

Temporary voltage drop below normal levels

Undervoltage (sag or dip) is a temporary decrease in voltage, often caused by large equipment starting up or overloaded circuits. You might notice lights dimming momentarily. SPDs cannot boost voltage - they only clamp high voltage. Computers may reset, motors may stall, and sensitive equipment can malfunction during voltage sags.

Voltage Surge

SPDs Protect Against This

Sudden voltage spike - what SPDs are designed for

Voltage surges (also called transients) are sudden spikes in voltage lasting microseconds to milliseconds. These overvoltage events are caused by lightning strikes, utility switching, and large equipment starting up inside your building.

Meter-Treater surge protection devices (SPDs) - also called surge suppressors - react in nanoseconds to clamp these voltage spikes before they damage equipment. Our Type 1/2 devices protect at the service entrance, while Type 3 units provide point-of-use protection.

Surge protection is the ONLY power quality issue that SPDs solve. For undervoltage, harmonics, or electrical noise, different solutions are required. Proper SPD installation requires grounding per NEC Article 250 and regular LED indicator checks.

Harmonics

Waveform Distortion

Distorted waveform from non-linear loads

Harmonics are distortions in the normal AC waveform caused by non-linear loads like computers, variable speed drives, and LED lighting. The waveform becomes distorted rather than a clean sine wave. SPDs don't address harmonic distortion. Problems include overheating transformers, nuisance tripping of breakers, and reduced efficiency.

Electrical Noise

RFI / EMI Interference

High-frequency interference on power line

Electrical noise is high-frequency interference superimposed on the normal power waveform. It comes from switching power supplies, variable frequency drives, and RF interference. SPDs with filtering capability help somewhat, but dedicated filters work better. Audio/video equipment, data transmission, and measurement instruments are particularly affected.

Voltage Swell

Sustained High Voltage

Temporary increase in voltage above normal

Overvoltage

High Voltage Event

Voltage exceeds normal operating range

Overvoltage occurs when voltage rises significantly above normal levels. Can be caused by utility regulation issues, transformer problems, or load imbalances. Equipment may overheat, fail prematurely, or experience immediate damage. While SPDs may activate, sustained overvoltage requires different solutions.

Choosing the Right Solution

If you're seeing equipment damage after storms or when power comes back on: If you're seeing equipment damage after storms or when power comes back on: You likely have a surge problem. Meter-Treater surge protection devices (also called surge suppressors or transient suppressors) are the answer. Install Type 1/2 devices at the service entrance for whole-building protection against lightning and utility switching transients. Add Type 3 suppressors for expensive equipment like pool pumps, HVAC systems, or commercial refrigeration.

If lights dim when equipment starts or voltage drops for extended periods: You have undervoltage or brownout issues. SPDs won't help. Look into UPS systems with voltage regulation, or investigate the root cause such as wire sizing or circuit loading.

If you need backup power during outages: SPDs provide no backup capability. You need UPS for short-term backup or generators for extended outages. However, these backup systems may need surge protection too, especially at points where AC and DC meet (disconnects, inverters). While an SPD won't provide backup power, it will extend the life of your backup system when load switching or induced surges might otherwise damage it.

If equipment shows interference, buzzing, or erratic behavior: You might have electrical noise or harmonics. EMI/RFI filters and power conditioners address this better than SPDs.

Important: Proper Installation and Grounding

When adding surge protection, it will not prevent sags, brownouts, or filter noise. If you experience these power quality issues after installing an SPD, have a certified electrician review the connections. You may also need a grounding audit - proper grounding is critical for SPD effectiveness. Changes to the grounding system can affect how well your surge protection works.

Understanding the Technology

SURGE VS. TRANSIENT

Modern standards use "surge" while older documentation calls them "transients." Both refer to brief overvoltage events. IEEE and ANSI standards often use both terms interchangeably.

SPD VS. SUPPRESSOR VS. TVSS

SPD (Surge Protection Device) - Current UL standard terminology
Surge Suppressor - Common industry term, still widely used
TVSS (Transient Voltage Surge Suppressor) - Older UL designation, phased out in 1998

All three terms describe the same protective equipment.

WHY METER-TREATER?

While terminology has changed, our core technology hasn't - we've been manufacturing surge suppressors since the 1980s. Whether you call them SPDs, suppressors, or TVSS devices, Meter-Treater products provide the same proven protection against voltage transients that has protected electrical systems for over 40 years.