Register Here | Login | My Account | Shopping Cart | Customer Service | Search| Items in Cart (0) | Quotes (0)
Call 1-800-369-6671
(Military/Intl Sales - 214-616-6180)

Vast Inventory for Fast Shipping. Custom Builds Available, Rentals and Sales.
Most items in stock for fast shipping!! UPS Ship Map Credit cards & Paypal Accepted
Home - Articles You're NOT logged in, Please log in   

Company Information

Product #:

ATEX and IEC Ex Flame-proof Explosion Proof Lighting & Equipment
Explosion Proof Lights
Explosion Proof Motors - Motors for Hazardous Locations
Industrial and Vaporproof Emergency Failsafe Lighting
Industrial Cord Reels and Tool Taps
Industrial Work Area Heaters
Machine Vision Lights
QC Series Industrial Portable Lighting - Quick Change Mount
Rig Lights
Stadium lights
String Lights and Temporary Light Stringers
Tank Cleaning Lights
Three Phase Motor Soft Starters
Vapor Proof LED Lights
Variable Frequency Drives (VFDs)
Vehicle Mounting Plates
Workboat Light Fixtures & Lighting Equipment
Yacht Engine Room Lights
Color Changing LED RGB Lighting
Explosion Proof Cord Reels
GOLIGHT Spotlights
Larson FUTURE - Lease Lighting
Remote Area Lighting and Scene Lights
Utility Bucket Mount, Receiver Hitch & Trailer Mount Lighting
Aevum Control Lighting and Equipment - IIoT
Butane and Solvent Extraction Room Lighting and Equipment
DC to DC Transformers and Power Supplies
Explosion Proof Fans & Blowers
Explosion Proof Paint Spray Booth Approved Lights
Explosion Proof String Lights
Explosion Proof Switchgear & Controls
Fleet Service Lights and Lighting Equipment
Industrial Equipment Trailers
Industrial Handlamps & Droplights
ISO 14644/FS-209E Clean Room Lighting
LED Blasting Lights
Night Time Fishing Lights
Portable AC Power Supply Units
Portable Power Distribution Panels
Power Distribution Panels with KVA Transformers
Self-Contained Lighting
Service Pit Lighting
Solar Generators & Solar Powered Lighting
Agricultural Farm Equipment Lighting & Beacons
Explosion Proof Cameras & Surveillance Systems
Explosion Proof Emergency Lights
Explosion Proof Heaters
Garage & Gas Station Canopy Lights
LED Grow Lights
LED Lights
NDT Ultraviolet Lights
Portable Hazardous Location Lighting
Radio Communication Towers and Equipment
Salt Water Processing Equipment
Shelter & Tent Lighting
Thermal Monitoring Cameras and Systems
48V LED Equipment Lights
ATEX Rated Explosion Proof Lights
Automotive Lighting
Class Rated Signals, Alarms, and Systems
Hazardous Location Area Lights and Portable Lighting
HID Equipment Lights
Hot Work Permit Lighting and Equipment
Hunting Lights
Industrial lasers
Industrial Transformers
Light Towers
Outdoor Lighting
Remote Security and Surveillance Systems
Temporary Construction Lights
Vehicle Mounted Spotlights
Equipment & Heavy Machinery LED Light Package Fitouts
Phase Converters - Single to Three Phase
Marine Shore Power Cords and Equipment
24 Volt Military Lights
Disaster Relief / First Responders / Search & Rescue Lighting
Plastic Handcuff Key
110/120 Volt Flood Lights
Post Mount Spotlights
Magnetic Work Lights
Crank-up Light Masts
Intrinsically Safe Lights
Military Flashlights
LED Waterproof Lanterns
Work Area Lights
12 Volt Flood Lights
Boat Spotlights
New Boat Lights
HID Boat Lights
Boat Dock Lights
Remote Control Lights
Control Lights
Tow Lights
Magnetic Control Lights
NEW Lights and New Products
Evaporative Coolers
Police Equipment
AC/DC Transformers
Power Supplies
Military Spotlights 24V
Infrared Filters, Covert Covers, and Blackout IR Lenses
Military Equipment
Ultralife Batteries
Remote Control Pan Tilt Base
Larson Electronics Spotlights
Larson Electronics Parts
Replacement Lamps
Cords - Brackets
Portable Wheeled Generators
Non-Hazardous Location Extension Cords / Plugs / Outlets
HID Work Lights
HID Dive Lights
HID Off Road Lights
Acro Lights HID Lights
Halogen Lights
Acro Light Flashlight
Xenon HID Flashlights
Powerlight Flashlight
HID Flashlights
Xenon Flashlights
LED Status Lights
Forklift Lights
Tractor Lights
HID Post Mount Lights
Roof Mount Lights
Post Mount Light parts
Flashlight Holder
Magnet Spotlight Base
Tripods-Magnetic Base
Recharging Spotlights
Fire Rescue Lights
LED Street Lights
Utility Lights
Hazard Lights
Strobe Lights - Battery Operated
Strobes & Beacons
Strobe Light Bars
Headlights - Headlamps - Hard Hat Lights
Suction Mount Lights
Magnetic Spotlights
12/24 Volt Spotlights
Gifts For Men
New 12 / 24 Volt Lights
Explosion Proof Accessories and Replacement Parts
Explosion Proof Lighting
Explosion Proof Hand Lamps (Drop Lights)
Explosion Proof Lights - Stand/Dolly
Explosion Proof Tank Lights
Explosion Proof Phones and Intercoms
Explosion Proof Extension Cords
Black Friday & Cyber Monday Specials
Crane Lights
Explosion Proof Light Rentals
General Light Rentals
Light Tower and Light Plant Rentals
Power Distribution Rentals
Power Plant Lighting
Refinery lights
Environmental Services Lights
Aerospace Lights
Chemical Plant Lights
Food Grade Safe Lights
Film and Entertainment Lights
Handheld Meters and Devices
Waste Water Treatment Lights
Mining Lights
Ship Yard Lights
Work Site Lighting

05/14/18 Calculating for KVA in Single and Three Phase Transformers

Article - May 14, 2018 By

30KVA Power Distribution Panel - 480V to 208Y/120V 3PH - Skid w/ Wheels

Calculating for KVA in Single and Three Phase Transformers

Need to size a single or three-phase transformer? Transformer sizes are dictated by their respective KVA rating. Using common variables, one can compute for the required KVA rating or transformer size for a particular project, system or operation.

This article provides basic formulas for finding the correct size of single and three-phase transformers using load voltage and load current.

Single Phase KVA Calculation

The formula for finding the required KVA or transformer size for single-phase power is the following:

Volts x Amps / 1,000 = KVA

Based on the equation, one would need to plug in the proper load/output (secondary) voltage and current (amps) to compute for KVA. Note that load voltage is not the same as line voltage, which is also known as primary voltage or input.

Example: Find the KVA or transformer size for load voltage of 120V 1PH and a load current of 50 amps.

120 x 50 / 1,000 = KVA

6,000 / 1,000 = KVA

= 6 KVA

Three-phase KVA Calculation

Businesses that require three-phase power need to add an extra component in the formula to arrive at the correct transformer size, i.e., square root of 3 (v3) or 1.732. This figure is a constant found in three phase, as the phases do not generate the same amount of power (simultaneously). Furthermore, three-phase transformers handle three lines of AC power, with each of the three lines 120 degrees out of phase from the other two lines.

With this in mind, the new formula can be found below:

Volts x Amps x v3 / 1,000 = KVA

Example: Find the KVA or transformer size for load voltage of 240 3PH and a load current of 60 amps.

240 x 60 x 1.732 / 1,000 = KVA

= 24.94 KVA (or 25 KVA after rounding up)

Future Expansion and Standard Transformer Sizes

Computing for the required KVA is not the final step in determining the proper transformer size. Most computations (especially for three-phase loads) do not provide a whole number. As a result, the value must be rounded up, as seen in the sample above. It is best practice to always round up and not down.

Next, in order to factor in future expansion and prevent risks associated with accidental overloading, one should add 20 percent of spare capacity. Taking the three-phase sample again, we simply add 20 percent to the rounded figure:

25 KVA + 5 = 30 KVA

Lastly, one may find that the specific transformer size needed is not being offered or is unavailable by the store or preferred manufacturer. In most cases, this is because there are standard KVA sizes for transformers. If you cannot find the size you need, simply round up again to the next standard KVA size.

For referencing, below are the standard KVA sizes for singe-phase transformers:

• 1, 1.5, 2, 3, 5, 7.5, 10, 15, 25, 37.5, 50, 75, 100, 167, 200, 250 and 333 (KVA)

Taking our answer from the single-phase example above – 6 KVA or 7.2 KVA (with 20 percent spare capacity); we can see that there is no standard single-phase equivalent available. As a solution, simply round up to the next standard single-phase KVA size: 7.5 KVA.

Standard sizes for three-phase transformers:

• 3, 6, 9, 15, 30, 45, 75, 112.5, 150, 225, 300, 500, 750 and 1,000 (KVA)

Taking our final three-phase figure of 30 KVA, we can see that it matches with a standard three-phase transformer size above, i.e., 30 KVA. No further rounding or conversion is needed, since 30 KVA is a standard three-phase transformer size.

Related Categories/Products
Category/Product (click on link below for more information)
Power Distribution Panels with KVA Transformers
Power Distribution Accessories and Replacement Parts
Portable Power Distribution Panels
300KVA Power Distribution - 480V to 208Y/120V 3PH - (1) L6-50R (1) L15-50R (4) 5-20R, Alum Windings
60kw Primary Distribution Panel - 120V/208Y - 100 Amp NEMA 3R Panel - Powder Coated Steel Frame
Explosion Proof Panelboard - 230-400V AC - 4 Circuit - 3 Phase 4 Wire - 40A Main Breaker - 14kAIC
25KVA Temporary Power Distribution - 480 or 240 Volt Input - 120/240V Output - (1) 240V & (8) 120V
Steel Equipment Cart - (4) 8" Casters - Powder Coated - Pintle Hitch - 24" x 36" Platform
Portable Spider Box - 125/250V Input - (1) 50A CS6369, (1) 30A L6-30R), (6) 20A L5-20R Twist Lock
C1D2 Power Distribution - 15KVA - 480V to 120/240V 1PH - (10) 120V Receptacles
Explosion Proof Portable Spider Box - 120V Input & Output - (10) 120V Outlets - Pin/Sleeve Cord Cap
30 Amp Fusible Manual AC Disconnect Safety Switch - 600V AC - 3-Pole
Low-Peak Time Delay Fuse - 600V AC -30A Rated
75 KVA Mobile Power Distribution - 480V to 208Y/120V 3PH - (1) 460R7W (1) 460R9W (6) 5-20R GFCI
Home | Contact Us | Return Policy | Privacy Policy | Security Policy | Copyright © 2006-2018. All Rights Reserved.