BIL

" BIL" means? in Electrical engineering?

BIL is Basic Impulse Level or sometimes some other referred to as "Basic Insulation Level".

It represents the "strength" of equipment's (transformers,motors)insulation for a high-voltage impulse. The impulse wave form is often 8 by 20 milliseconds -- An 8 ms rise and 20 ms in duration.

Here is a quote from C57.12.00:

"Transformers shall be designed to provide coordinated low-frequency and impulse insulation levels on line terminals and low-frequency insulation levels on neutral terminals. The primary identity of a set of coordinated levels shall be its basic lightning impulse insulation level (BIL)."

Each voltage class of equipment has a ANSI standard BIL rating. For example: 15 kV is the most common distribution voltage class in the US. Equipment installed on a 3-phase, 4-wire circuit in the 15 kV class with have a BIL rating of 95 kV. (The 15 kV class includes voltages from 11.8 kV through 14.4 kV. The most common actual system voltages are 12.47, 13.2, and 13.8 kV.)

The appropriate rating depends on whether the equipment is effectively grounded and/or connected to a 3-wire or 4-wire system. Some of the more common BIL ratings used on distribution equipment in North America are 60, 95, 125, 150, and 200 kV.

Transmission and substation equipment has a minimum BIL rating of 110 kV. Here are some of the minimum BIL ratings for various transmission voltages:

System - BIL
138 kV = 450 kV
230 kV = 650 kV
345 kV = 900 kV
500 kV = 1130 kV
765 kV = 1800 kV



Source(s):
C57.12.00 - IEEE Standard General Requirements for Liquid-Immersed Distribution, Power, and Regulating Transformers

Faulty Electrical Wiring

There is no such thing as faulty electrical wiring according to some electrical engineers due to the fact that it cannot be operational in the first place.

However, I disagree we have to be specific and know the fact when we used the term “Faulty electrical wiring” .

Here are some instances.

Do you think you may have a problem with your electric wiring? Did you know that there are more than 40,000 fires caused by bad wiring or improper use of electric cords and appliances.

If you’re concerned about your home wiring, here are some tips about what causes electric fires, what the signs may be and a recommendation from the Consumer Products Safety Commission about how to help protect yourself.

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We know: Signs of Faulty Electric Wiring

Be Aware and Know the Facts

Is an older house more at risk for wiring problems?

Half of the nation’s housing stock is more than 30 years old. Many older homes were not designed to meet current-day electricity demands. An older home doesn’t necessarily mean a hazardous home, but if you live in one, you should be aware that wiring could be a problem.

What are the problems with older homes?

Homes that are 100 years or more old, were wired at 30 amps. By mid-century, that had increased to 60 amps. More recently, homes have been wired at 150 to 200 amps. Some new homes are wired at 800 amps.

If your home was wired before the 1950s, it may have poor wire insulation, ungrounded (2 prong) outlets, and fuse boxes instead of circuit breakers. All of these things increase the risk of fire and accident.

http://www.ineed2know.org/ElectricWiringTips.htm