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In the United States, impact attenuators are tested and classified according to AASHTO Manual for Assessing Safety Hardware (MASH), [13] first issued in 2016 to supersede National Cooperative Highway Research Program (NCHRP) Report 350: Recommended Procedures for the Safety Performance Evaluation of Highway Features (1993). [14]
Within NCHRP 350 there are six separate test levels (TL) representing different vehicles, impact angles, and speeds. Test level three (TL-3) is probably the most common as it establishes safety criteria for both small cars and pickups at 60 miles per hour (97 km/h). This category of traffic accounts for the majority of all vehicle traffic in ...
Another anecdote contributing to NCHRP's founding comes from the late 1950s when it was noted that 32 state DOTs were researching the same topic without any knowledge of each other’s work. This revelation provided incentive for the states to pool their resources on a national research program addressing common problems.
For a typical coaxial cable, loading is of the order of 100pF per meter (the length of a typical test lead). Attenuator probes minimize capacitive loading with an attenuator, but reduce the magnitude of the signal delivered to the instrument. A 10× attenuator will reduce the capacitive load by a factor of about 10.
Jersey barriers on the road. A Jersey barrier, Jersey wall, or Jersey bump is a modular concrete or plastic barrier employed to separate lanes of traffic.It is designed to minimize vehicle damage in cases of incidental contact while still preventing vehicle crossovers resulting in a likely head-on collision.
Preferred attenuators use either doped fibers, or mis-aligned splices, or total power since both of these are reliable and inexpensive. Inline style attenuators are incorporated into patch cables. The alternative build out style attenuator is a small male-female adapter that can be added onto other cables. [3]
EFT test levels (IEC/EN 61000-4-4) [4] Power ports, earth ports (PE) Level: Voltage peak (kV) Repetition frequency (kHz) 1.5 kV: 5 or 100 kHz 2: 1 kV: 5 or 100 kHz 3: 2 kV: 5 or 100 kHz 4: 4 kV: 5 or 100 kHz x: special: special x can be any level specified in product specific standards
The European Standard EN 62262 — the equivalent of international standard IEC 62262 (2002) — relates to IK (impact protection) ratings. [1] This is an international numeric classification for the degrees of protection provided by enclosures for electrical equipment against external mechanical impacts.