حفاظت مدار جافیوز(پایه فیوز)

Product Attributes

Introduction

The following guidelines help simplify the selection of the appropriate fuse holder:

1. Determine System Voltage Since fuses are selected based on system voltage, the fuse holder selection should match the voltage rating of the fuse.
2. Determine the Design Short-Circuit Current The available and/or design short-circuit current is an important consideration when determining the class of fuse and fuse holder to use. If the available short-circuit current cannot be determined, or if it varies with equipment location, then for maximum safety, fuses with a 200,000 ampere interrupting rating (A.I.R.) and matching fuse holders with a 200,000 ampere withstand rating should be selected. Class H fuse holders accept Class H or Class K5 fuses (interrupting rating up to 50,000 amperes) and Class R fuses (200,000 A.I.R.). To prevent insertion of fuses with an incorrect interrupting rating, it is recommended to use Class R fuse holders with Class R fuses, and Class H fuse holders with Class H or Class K5 fuses. These fuse holders are identical in size, but Class R fuse holders feature a rejection function that only allows Class R fuses to be inserted.
3. Determine the Fuse Type and Ampere Rating to Use In addition to the voltage and interrupting rating discussed above, the fuse's ampere rating, time-current characteristics (fast-acting or time-delay), and size are other important considerations in fuse selection. Once the fuse type is selected, the matching fuse holder can be chosen. Fuse holders are available in 30, 60, 100, 200, 400, and 600 ampere ratings and can be used with fuses of the corresponding or lower ampere rating. For example, a 30-ampere fuse holder can be used with fuses rated from 0 to 30 amperes.
4. Determine Whether NEC, CSA, UL, or Other Requirements Apply If the fuse holder will be installed in equipment requiring agency certification, the relevant requirements should be obtained from the certifying agency before selecting fuses and fuse holders.
5. Select the Wire Terminal Type Three wire terminal types are available: a) Screw — For use with spade terminals or ring terminals. b) Screw with pressure plate — For use with solid or stranded wire without terminals. Recommended where vibration is a factor. c) Box connector — Most durable. Suitable for all types of solid wire and Class B and Class C stranded wire. Not suitable for welding cable or other rope-stranded conductors. On Midget and Class CC fuse holders, 1/4-inch quick-connect terminals rated up to 20A are available.
6. Determine the Number of Poles per Fuse Holder The number of poles per fuse group is determined by circuit characteristics. The option to combine individual fuse holders into a strip will depend on available space and the type of wire used.
7. Determine Whether Reinforced Fuse Clips Are Required Fuse clips may lose some tension over time. This can be prevented by specifying reinforced fuse clips. Reinforced clips are standard on certain fuse holders (refer to the individual product pages).

Class G fuse holders are designed for use with 480-volt time-delay, current-limiting Class G fuses. They meet the requirements for branch circuit protection. Note: For dimensions of the L30030G 30A Class G fuse holder, refer to the Midget/Class CC fuse holder.