Insulator approved

Tests on Cable Constructions. The Association of Edison Illumination Companies (AEIC) has approved an accelerated cable hfe test in which typical underground distribution power cables can be statistically compared based on their resistance to water treeing (number of days to fail). The comparison can be made by varying the type of insulation and/or other cable layers in an environment that contains hot water (90°C) under 8V/fi (200 V/mil) voltage stresses (four times the typical power cables operating voltages). 

Steel stmctures should be protected by approved fireproofing treatment, eg, concrete or insulating, ie, intumescent or ablative materials untreated steel should be protected by some method of cooling, eg, a water-spray system. 

Another method to meet the safety specifications is the use of triple-insulated wire for the secondary windings. Its use can reduce the transformer s size and leakage inductance compared to the border-tape method. Triple-insulated wire has three distinct, approved layers of insulation and it may be wound directly in contact with the primary windings. Whether Mylar tape is needed in or around the transformer depends upon the insulation system used in its construction. This type of transformer can be seen in Figure 3-25. 

I will be using an E-E eore with the neeessary Mylar tape insulating layers to meet the isolation requirements of the safety approval ageneies. At these operating frequeneies, a high-frequency core material will have to be used to minimize the core losses at 1 MHz. The material should be the K material from Magnetics, Inc, 3C85 material from Phillips, or N67 material from Siemans. 

This section of Approved Document L does not have any relevance to insulation. 

Utilization of slave labor in Farben was approved as a matter of corporate policy. To permit the corporate instrumentality to be used as a cloak to insulate the principal corporate officers who authorized this course of action is, in my opinion, without any sound precedent under the most elementary concepts of criminal law. 

Figure 1 indicates a typical nitroglycerin facility "inside out" wood frame construction at a concrete floor slab. Note that the exterior cant strip, the lead conductive floor cant and the wood cap are all sloped to discourage product build-up and facilitate cleaning. This assembly also indicates spray-on foam insulation as an optional construction item. At Radford AAP this is a safety approved insulation system. The insulation at Radford AAP received a chlorinated rubber paint coating for weathering. 

They are insulated with approved noncombustible materials such that the average temperature of the unexposed side will not rise more than 180 oC above the original temperature, within the time listed (i.e. A-60 60 minutes, A-30 30 minutes, A-15 15 minutes, A-0 0 minutes). 

Method B—This is the same as Method A except that 1 in (25 mm) thick mineral wool insulating board, with a density of 6 to 8 Ib/ft (96 to 128 kg/m ), should be glued to the bottom of each tray to separate the instrument lines from the sheet metal tray. Also, the outside of the tray should be coated with approved intumescent mastic (sin (4.8 mm) dry thickness. 

Polyurethanes can be considered safe for human use. However, exposure to dust, generated in finishing operations, should be avoided. Polyurethanes are combustible. An approved fire-resistive thermal barrier must be applied over foam insulation on interior walls and ceilings. Under no circumstances should direct flame or cxocssivc heat be allowed to contact polyurethane or polyisocyaiiurale foam. 

Small shipments of ethylene oxide are made in either compressed gas cylinders up to -0.1 m3 (30 gal) or in 1A1 steel drums (61 gal). Very large shipments >40 m3 (10,000—25,000 gal) are made in insulated, type 105J100W or other DOT approved tank cars. For further information on the shipping and handling of ethylene oxide, see References 9 and 227. 

The basic electrical properties of polyurethanes are good, but the polymer s tendency to absorb moisture can change the properties considerably. Polyurethanes are therefore not normally used as electrical insulators. They can be used in potting and encapsulating applications. Any applications involving mains power must be evaluated and approved by the relevant local electrical authority before use in the application. 

Measurement of flame spread under external heat flux is necessary where the thermal radiation is likely to impinge on the textile materials, for example, the flooring material of the building or transport vehicles whose upper surfaces are heated by flames or hot gases, or both. The French test method, NF P 92-503 Bruleur Electrique or M test involves radiant panel for testing flame spread of flexible textile materials. This test method (flame spread under external heat flux) is the basis of that used by the FAA (Federal Aviation Administration) for assessing flammability of textile composites used in thermal/acoustic insulation materials (FAR 25.856 (a)) used in aircraft and has also been included by the EU for fire test approval of floorings such as prEN ISO 9239 and BS ISO 4589-1. 

Building Insulation Materials Compilation by J.G. Bourne, D.L. Brownell, E.C Guyer, R.C. Thompson, and R.P. Tye, Dynatech R/D Company, Cambridge, MA, for the Naval Civil Engineering Laboratory, Port Hueneme, CA. September 1979, Approved for Public Release. Contractor Report No. CR 80.001, 137 pp. 

For approved water spray with approved insulation 0.15... 

The International Electrotechnical Commission (lEC) was founded in 1904 and is now affiliated with the International Organization for Standardization as a Technical Division. The lEC has a Technical Committee 15 on Electrical Insulating Materials, which is concerned with the standardization of testing methods and specifications in this special field. It met in Scheveningen, Netherlands, September 10 to 12,1952. Approved test methods and specifications are issued as recommendations and standards (16),... 

As part of the R.C.S. program, specifications for approved insulation products will be provided to the utilities. That same data will be used by the Internal Revenue Service with regard to its tax rebate program, should it continue. 

Note It is not mandatory to use a particular thickness of insulating tape, provided it is safety-approved to withstand a specified voltage. We can, for example, use 1 mil approved tape or even 1/2 mil, if it suits our production, helps lower the cost, and/or improves performance in some way. 

Levels of protechon that are considered essenhally equivalent are a) earthing of any exposed metal surface, b) physical separahon (typically 4 mm) between any exposed metal and parts of the circuit containing high voltage, and c) a layer of approved insulator between any exposed metal and the high voltage. Note that the insulator must have a minimum dielectric withstand capability of 1500 V ac or 2121 V dc. 

But consider the case of a high-voltage mosfet (switch) mounted on the (earthed) metal enclosure (for better heatsinking). Clearly, we can t provide any level of protection through physical separation. So in this case, we need to place one layer of approved insulator between the mosfet and the enclosure. Note that in this position, the insulator serves as basic insulation. ... 

What if we have an exposed conductor that is not connected to earth (such as for equipment with a two-wire ac cord), or if earthing is itself not an acceptable level of protection for that particular type of equipment as per safety regulations Then, besides the layer of basic insulation, we need another insulating layer (with identical dielectric withstand capability). This is called supplementary insulation. Together these two layers (basic + supplementary) are said to constitute double insulation. We could also use a single layer of insulation, with dielectric withstand properties equivalent to double insulation (i.e. 3000 V ac or 4242 V dc). That would then be called reinforced insulation. So for example, if the equipment is by design, meant only for a two-wire ac cord, we would need two layers of approved insulators (or... 

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