Five Things You Should Know About Transformer Rectifier Units
When shopping around for a transformer rectifier unit (TRU) or set of transformer rectifier units, there are a few things you will want to consider. You will obviously want to pay close attention to the military standards of the rectifier unit and the very specific job the rectifier unit will be used for. Above and beyond that, there are essentially two standard types of harmonically corrected transformer rectifier units available on the market.
These include:
- Unregulated unites with a power factor correction and power levels from 100 Watts to 100,000 Watts
- Regulated unites that have power levels from 1000 Watts to 15,000 Watts (these are good for providing output voltage regulation for varying line and load conditions).
All the off-the-shelf transformer rectifiers should operate within the most stringnet and weather intensive environments possible. These units should be qualified for military standards and for 'mission critical equipment' as it is sometimes referred to.
Other questions to consider when shopping for a transformer rectifier unit are:
- Is the unit MIL-STD-461, MIL-STD-704 compliant?
- Does the unit have passive power factor correction?
- What is the low parts count for high MTBF?
- Is the construction built for rigorous testing and is it MIL-STD-810 compliant?
- Is the rectifier unit compliant for both conduction and air cooled?
When buying transformer rectifier units with environmental and strenuous concerns in mind, make sure the construction meets the MIL-STD-810 standard for vibration, shock, acceleration, fungus, sunshine and altitude. This should also mean that whether you are in the sand, dust, humidity, saltspray, rain, or even explosion environments you are buying a quality transformer rectifier unit with the ability to withstand all of the above.
There are a few things to consider about transformer rectifier units when it comes to their power rating. For one thing, the harmonic current limits in MIL-STD-461 are based upon a percentage of the fundamental currents at a full load. Most transformer rectifier units are designed to be compliant with a full rate resistive load. This means that you should always exercise caution when you select the power rating of the rectifier unit. This is essentially so you do not 'overspecify' because a converter operating way too far below its rating may actually draw harmonic currents in excess of MIL-STD-461 limits when compared to the actual delivered power of the unit.
There is a lot to know about transformer rectifier units before you decide to purchase one. Just remember that it is important that the unit meets specific military standards (MIL-STD's) as mentioned above. You will want to shop around in order to make sure you are getting the rugged unit you desire for the specific job you have in mind, but just make sure the company you do business with is ISO compliant and is available to answer all of your questions in a timely fashion.
About the Author:
John is Webmaster for Abbott-Tech.com. For more information regarding transformer rectifier units and military grade transformers and military power supplies Abott-Tech.Com
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