3. Low-Voltage Power System Basics · Page 6 of 6
Power Quality vs Surge Protection
Do not confuse harmonics filters with SPDs.
Different problems
Harmonics, flicker, and voltage sags are power-quality topics. Surges are high-energy, short-duration overvoltages. Solutions are not interchangeable.
Complementary tools
A site may need SPDs plus UPS, filters, or AVR. Specify each for the disturbance it actually solves.
Specification tip
Write separate line items: "LV power SPD per IEC 61643-11" and "power quality mitigation," so contractors do not substitute one for the other.