Types of Fuses

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Several types of fuses are available for various applications in motor control systems. The two main types of fuses are cartridge and plug fuses. Figure 1 shows several cartridge and plug fuses in different sizes. Some of these fuses provide blades to make connections in the fuse holders, and other fuses provide connections at the neck of the fuse. The plug fuse comes in several sizes, embossed on the current rating of the fuse. A rejection feature is provided on cartridge, blade, and plug fuses. Examples of the rejection features are also shown in this figure. The rejection feature prevents a fuse with a larger current rating from being substituted for the fuse of a smaller size that was originally specified.

This is accomplished by providing a matching rejection feature in the fuse holder that is mounted in the fuse box with the feature that is provided for the fuse size. That is, each size of fuse has a different type of rejection feature, or it's located at a different point on the fuse body for each amperage rating.

HI-CAP (Time-Delay) KAP-c (600V) 601 to 6000A soo,000Alc current Limiting Ui class 1; CSA-Hnc-L The a silver linked tune for both overload & short-circuit protection ot high capacity systems (mains & large teeders(. Time-delay (minimum ot tour seconds at five times amp rating br close sizing. Unlike last-acting tuaes, pass harmless surge currents 01 motors, transform- em etc., without overluaing & any sacrifice or short-circuit current limitation (component protection(. The combination use ot ‘Ira to 600 ampere LOW-PEAK daal element time-delay tunes & 6011 6000A KRP-C HI-CAP tunes is recommended as a total system apecitication. Easily selectively coordinated br blackout protection. Size ot upstream fuse need only be twice that of downstream HI- CAP or LOW-PEAK loses (2:1 ratio). HI-CAP tunes can re duce bus bracing: protect circuit breakers with low interrupting rating as well as pro vide excellent overall protec tion ot circuits & loads. LIMITRON® (Past-Acting) KTU (BOGy) 601 to 6000A Current Limiting 200,000AIC UL Class L: CSA-HAC-L Silver-linked fuse. Single- element units with no time- delay, Very last-acting with a high degree of current limitation: provide escellenl compo nent protection. Particularly suited for protection of circuit breakers with lower interrupting ratings, & non-inductive ioada such as lighting tad heating circuits. Can be used for short-circuit protection only in circuita with the inrush cur mnts; Must be oversized to prevent opening by the tem porary harmless overloads with some sacritice ot cument limitation. In motor circuits, must be size at approai mafely 300% of motor tut load currenf & thus won't provide the overload protec tion of HI-CAP KRP-C tunes. LIMITRON® (Time-Delay) KLU (600V) 601 to 4000A Current Limiting 200.000AIC UL Class L: CSA-HAC-L 10 seconds delay (minimum) at 500% of amp rating- Not at current limiting as KRP-C or KTU fuses.
(Dual-Element, Time-Delay) FRS-R (600V( FRN-Ft (250V( ‘ to 600A 200,000AIC Current Limiting UL Clans RKS: CSA-HRC-l (0 Time-delay all orda the same excellent overload protection 01 LOW-PEAK fuses of motors & other type loads & circuits having temporary in rush currents such as caused by transformers & sole noids. (In such circuits, LIMI TRON fuses can only provide short-circuit protection). FUSETRON tunea are not aa fast-acting an LOW-PEAK fuses & theretore can't give as high a degree ot com ponent short-circuit protection. Like LOW-PEAK tunes, FUSETRON tunes permit the use of smaller size & lent costly switches. PUSETRON tunes fit rejection type fuse- holders & can also be in stalled in holders br Clans H tunes. They can physically & electrically replace Clans H. KS, & other Class RKS tunes. ONE- (General Purpose) N05 (600V( NON lQSflV) LIMITRON (Past-Acting) KT5-R (600V( KTN-R )250V) to 600A 200,000AIC Current Limiting UL Clans RK1: C5A HRC-t Single-element, last-acting tunes with no time-delay. The name basic performance ol the 601 -6000A KTU tast acting LIMITRON tunes. Pro viden a high degree of short- circuit current limitation (component protection). Particularly suited for circuits & loads with no heavy surge curren of motors, branstorm em, solenoids, & welders. LIMITRON fuses are com monly used to protect circuit breakers with lower interrupt ing ratings. It used in circuits with surge currents (motors, etc.) must be oversized to prevent opening & thus only provide short-circuit protection. Incorporate Class A rejection lealure, Can be inserted in non-rejection type fuse holder. Thus, can physically & electrically replace last acting Clans H, K1. KS, RKS, & other RK1 tunes. LOW-PEAK (Dual-Element, Time-Delay) LPS-RK )600V) LPN-RK )2S0V) ‘Ira to 600A 200,00CAIC Current Limiting UL Class AKI: CAS HRC-t (D) High performance, all- purpose tunes; Provide the very high degree 01 short- circuit limitation 01 LIMITRON tunes plus the overload protection 01 FUSETRON tunes in all types of circuits & loads. Can be closely sized to full-load motor currents br re- liable motor overload protection as well an backup protection. Close sizing permits the use of smaller & more economical switch)and tunes): better selective coordination against blackouts: & a greater degree of current limitation (component protection), LOW-PEAK tusen are rejection type but tit non-re(ection type tuseholdems. Thus, can be used to replace Class Ft. Ki, KS, AKS or other AK1 tunes. in to 600A 1 0,000AIC Non Current Limiting UL Class H (K-S in Sizes t-60A With an inter 10,000 amp not considering. Clans H are used in available short- Single-element tunes don't delay. The 1- a 50.000 AIC, Class K-S.
Above: Fig. 1 Types of cartridge and plug fuses available for use in industrial circuits. These are Buss Power Distribution Fuses from Bussmann.
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