UPS Power Inverter and DC to AC

Learn about Power flow, Sags, Dips, Phase rotation, Harmonics, Flicker and more!

Power Quality Teaching Toy

Standards

CBEMA – Computer Business Equipment Manufacturer’s Association adopted curve IEEE Standard 446 (orange book) curve. Recommended Practice for Emergency and Standby power systems for Industrial and Commercial Application.”

• Wave form Sine wave THD (total harmonic distortion) maximum 5%.
• 3 Phase system phase imbalance of voltage 3% – 6%.
• Frequency stability 60  +/- 0.5Hz.
• Output Voltage +6% Max. -13% Min. from Nominal Value.
• Voltage can fall to 0V but should recover in 0.5 Cycles.
• On turn on Voltage should reach steady state within two seconds.
• Upto 200% over Nominal Voltage should be tolerated for 100uS. ( Transients, spikes and Inductive Kickbacks come in this)
• Upto 30% over Nominal Voltage should be tolerated for 0.5S.

ANSI – American National Standards Institute

“Standard Voltage Ratings for Electrical power systems & Equipment”

• Steady State Variations +/- 5% of Nominal Voltage. T
• Three Phase Voltage Imbalance 5% Max..
• Standard Frequency 60Hz.

Glossary

• Frequency 60Hz Hz is Hertz.
• One Cycle = 20mS (milliseconds) one full sine wave.
• Max – Maximum
• Min – Minimum
• uS – micro seconds, S – seconds.

Cause of Transients

1. Switching Loads Simultaneously (inductive loads).
2. Power factor correction capacitors and devices.
3. Lightning strikes (enhanced by earth faults).
4. Line Inductance (inductive kickback, resonance).
5. DC and AC Drives for Motors.
6. Rectifiers with large filters and stray inductance.

CBEMA Guideline
The CBEMA guideline, created by the Computer Business Equipment Manufacturers Association is a realistic, at-the-equipment, maximum allowable voltage that equipment can withstand, without damage or upset.