|
|
|
3rd Edition
LIMITED CURRENT ABNORMAL OVERVOLTAGE TESTS
Followed by: Fascinating Facts -
"Test your Storm IQ" |
February 2010 |
|
CONGRATULATIONS Pat Garrity
United Electric Supply, Omaha, NE -
winner of the Hannspree Digital Photo Frame.
Pat was the first to correctly complete the following sentence:
'In 3rd Edition, Type 3 devices are cord connected or direct plug in type devices while Type 4 are considered component or partial assemblies requiring an enclosure.'
Answer can be found in the SSI 3rd Edition #4 Newsletter -
"Where Do The Ratings Come From?" released 7-27-2009
( Link to newsletter archive) |
|
|
Read any good books lately?
Be the first to correctly answer the
3rd Edition challenge question below to
win a $25.00 Barnes & Noble gift card.
|
|
Special Edition Featured Article:
Standard for Surge Protective Devices
'Limited Current Abnormal Overvoltage Tests" |
To recap some of our previous discussions, we have looked closely at the various ratings required by UL 1449 Third Edition. These included the Nominal Discharge Current Ratings (IN). As you will recall, the IN Rating is derived from the Nominal Discharge Current Tests which are based on an 8/20 µs current waveform. During these tests, the current is impressed through the device at the specific values declared by the manufacturer. For example, a Type 1 device is tested with either 10 or 20 kA impressed through the device.
As stated previously, the Limited Current Abnormal Overvoltage Test, the Intermediate Current Test and Short Circuit Current tests in Third Edition are done using an abnormal overvoltage and available fault current rather than a specific current value impressed through the device.
The available fault current utilized in these tests varies based on SPD Type and the specific test being conducted as shown below.
This article will focus on the rationale supporting the Limited Current Abnormal Overvoltage Test.
Brief Test Description utilizing the parameters for a 120V circuit only for purposes of this discussion
|
CURRENT TEST |
SPD TYPE |
TEST VOLTAGE |
CURRENT |
|
Limited Current Abnormal Overvoltage |
Type 1 SPD
Type 2 SPD
Type 4 used in a Type 1 or Type 2 application |
240 V |
10, 5, 2.5, 0.5 A |
|
Limited Current Abnormal Overvoltage |
Type 3 & Type 4 |
240 V |
5, 2.5, 0.5, 0.125 A |
|
If pass criteria is met as per the standard, then Leakage Current or Grounding Continuity tests are performed based on SPD design. |
The purpose of this specific test is to ensure that when a limited current fault occurs on the line, the SPD will respond in an appropriate manner.
This type of fault can occur in installations where the SPD is installed on the load side of a very small transformer, or in an installation of an SPD deep within a facility. In both cases, the amount of available fault current may be very small. This limited current fault condition is discussed as well in IEEE C62.72-2007 with specific reference to a phase-to-ground fault. It is stated that "the current flow is usually quite low and typically only ranges from 1A to 20A." Finally, the residential application may be the most common occurrence of a limited current fault condition in which the neutral is open. Each of these events has the potential to result in an increased overvoltage scenario (abnormal overvoltage).
Again, In all cases, the pass criteria for the Current Tests are as follows:
During and following the tests, the following conditions shall NOT result -
- Emission of flame, molten metal, glowing or flaming particles through any openings (pre-existing or created as a result of the test) in the product,
- Charring, glowing or flaming of the supporting surface, tissue paper, or cheesecloth,
- Ignition of the enclosure,
- Creation of any openings in the enclosure that result in accessibility of live parts, when evaluated in accordance with the accessibility of live parts test in 58.2,
- Loss of structural integrity to a degree that the equipment collapses or experiences such displacement of parts that there is a risk of short-circuiting or grounding of current carrying.
The overall purpose of these tests is to ensure that when an SPD is subjected to an abnormal overvoltage anomaly, regardless of whether the anomaly takes place with a low, medium or high available fault current, the device responds appropriately and does not create a fire or shock hazard. |
|
COMING SOON...
...Another informative 3rd Edition discussion!
Be the first to answer the following
question correctly and win a
$25.00 Barnes & Noble gift card:
"In regards to 3rd Edition SPD certification/listing, as long as the organization providing the listing or certification is a _________, it is deemed acceptable."
your contact information today. Good luck!
(Contest excludes employees/distributors/resellers of SSI)
|
Click on link to inquire about anything related to 3rd Edition. Submittals have a chance to be featured in a future newsletter!
|
|
Fascinating Facts: |
|
|
Test Your Storm IQ
As Reported by: Sky Fire Productions, Inc. |
 How hot is lightning?
Some like it hot...and they should just love lightning.
The air in the core of a lightning bolt has been
estimated to be heated to as much as 54,000°F
(30,000°C). That happens to be about six times hotter
than the surface of the sun.
Can there be lightning during a snowstorm?
Lightning is usually associated with thunderstorms, and therefore is thought to be a spring and summer event. Yet lightning does occur during winter, and even during heavy snowfalls and blizzards. Winter lightning appears to be unusually powerful, associated with loud and long thunderclaps. Sometimes associated snowfalls can reach 3 inches an hour. A man was struck by lightning during a blizzard in Minneapolis during March of 1996. He is still alive...and very puzzled.
What is ball lightning?
Ball lightning is one of nature's most mysterious phenomena. Usually seen during violent thunderstorms, the spheres of glowing light are typically the size of bowling balls or basketballs. They can last from a few seconds to many minutes. The spheres can simply vanish into thin air but can also pass through window glass and screens leaving burn marks behind. Not every scientist is convinced the phenomenon even exists. But there are numerous credible reports of "balls" of "fire" floating through the air, often after nearby lightning strikes. They usually do not cause much damage and even seem "playful". They have been known to roll down the aisles of airliners or pass through an open window into a startled resident's bedroom.
Are thunderstorms the only source of lightning?
Lightning is usually associated with thunderstorms. On a few occasions, it has been observed within giant steam and debris clouds from erupting volcanoes. Lightning, and even miniature tornado-like vortices attended the spectacular volcanic birth of the island Surtsey, near Iceland. Giant plumes of smoke from large forest fires also have been known to produce lightning, although these smoke clouds were probably in the process of turning into regular thunderstorms. In the western U.S., most forest fires are started by lightning. Sometimes the heat from the intense fires trigger new thunderstorms ... which in turn can produce more lightning. This is called a feedback loop.
If a lightning flash takes only a fraction of a second, how come thunder lasts so long?
While we see the flash virtually instantaneously, the beginning and end points might be 5 or more miles separated. Due to the slower speed of sound, it takes differing lengths of time for the shock wave to reach our ears. If the lightning channel was two miles long, and assuming it started directly overhead, it would take at least 10 seconds for the rumbling to stop.
How loud is thunder?
Sound intensity can be expressed in decibels (sometimes abbreviated dBA). A clap of thunder can typically register about 120 dBA, or ten times louder than a garbage truck, chain saw or pneumatic drill. On the other hand, sitting in front of the speakers at a rock concert can expose you to a nearly continuous 120 dBA, which can seriously harm your hearing. | |
|
|
|
|
| Link to Newsletter Archive |
Surge Suppression Incorporated®
a premium product at a fair price.
ISO 9001:2008 Certified Manufacturing Facility
Click on this link to view a three-minute movie about SSI.
Looking for a distributor or reseller in your area?
For more information or assistance, please contact your local Surge Suppression Incorporated® representative
or contact us at
888-987-8877
|
|
|
|
|
