Understanding Inverter Output Power Ratings

Inverter output ratings are traditionally defined in terms of Apparent Power in VA (Volt Amps) & Power Factor. Apparent Power is the product of the maximum output volts & amps available under the most favourable operating conditions for the inverter. This maximum operating point is defined by the Power Factor; the Real Power available in watts is the maximum VA multiplied by this said Power Factor. Real power is the effective power value as if the V & A were in phase & the PF =1 as would be the case if the load was an electric fire bar or a fully power factor corrected power supply.

Probably one of the most basic definitions of power factor is that it equals the cosine of the phase angle between the voltage & current. This is difficult to conceptualize in terms of the input to a non PF corrected power supply because besides the current phase leading the voltage its whole waveshape changes from a sine wave to a series of current peaks. Both effects are due to the large storage capacitance following the input rectifier. This greatly complicates the issue but plays a large part in the reason for the traditional rating method for an inverter.

In many older non corrected power supplies the power factor may be considerably less than 1, say down to 0.6. Even today there are many smaller power computer/server power supplies which only have passive PF correction giving power factors in the region of 0.8-0.9.

It is very important to ensure the inverter is sufficiently rated to drive the load. Consider an inverter having a VA rating of 1000 & power factor of 0.8 giving a real power limit of 800W. Neither the VA rating nor the real power watts rating can be exceeded. If the load PF is greater than 0.8 then the power limits remain as previously defined, however, if the load PF is less than 0.8 the real power limit will be further reduced.

For information on the full line of UNIPOWER Sinewave Inverters go to: http://www.unipowercorp.com/Unipower_Telecom/Telecom_Product_Line/Telecom_Inverters/telecom_inverters.html

HASS Screening For Power Supplies

Here at UNIPOWER we use HASS or "Highly Accelerated Stress Screening" during the production process to improve the quality of our products. The purpose of HASS is to shake out manufacturing and component defects before shipment to our customers. It is an important element of our Quality Process and an integral part of the production process.

UNIPOWER has been using HASS successfully for over 17 years and has developed a significant amount of expertise in determining the best screening profiles specific to high-density power supplies and systems.

The HASS Profiles designed and used by the company include low temperature, or -15 degrees Centigrade turn on and power cycling, rapid temperature rise while under power to +55 degrees Centigrade, high temperature turn on and power cycling, and two 7 minute vibration cycles at different temperatures. The most used profile runs 30 minutes.

The ultimate goal is to find out problems long before our customers find them and HASS is a much better screen than the typical 4, 8, 12 or 24 hour burn-in process used by most power supply manufacturers today.

DC Distribution Panels Shipped in 24 hours

UNIPOWER has developed a program that allows customer configured DC breaker panels and DC fuse panels to ship within 24 hours.

For a period of now six consecutive months, UNIPOWER has consistently been able to take orders, configure and ship in less than one day. This flexibility represents and tremendous advantage to customers getting ready for an installation.

Essentially integrators or customers in the field can quickly view the options and possible configurations available from UNIPOWER on the website, call in an order, and feel comfortable about the fact that the shipment will be out the same day or the day after.

More information at : http://www.unipowercorp.com/Unipower_Telecom/Telecom_Product_Line/Distribution_Panels/distribution_panels.html

12VDC Custom Power Solution

UNIPOWER Corporation has successfully developed a modification of it's TPCM Series product which can now supply 780 watts of power at 12 VDC, increasing power density by 20%.

At the request of a strategic customer, UNIPOWER Corporation successfully developed a customized power solution effectively allowing the customer's next generation product to utilize the existing mechanicals and power configuration. This achievement anchors UNIPOWER’s capacity to provide custom power solutions in addition to a broad standard product offering.