Transformer Fuses Protection Rated
E Rated fuses provide transformer protection and are medium voltage, current limiting general purpose power fuses that provide overload and short circuit protection. E Rated medium voltage fuses are designed to withstand the large magnetizing inrush that occurs during transformer start-up.
E Rated fuses are available in Bolt In Mount Clip Lock Mount and Ferrule Mount versions and have blown fuse indication. Voltage ratings range Missing: christmas. AB4D0RE from Mersen at Allied Electronics & Automation. Description. Fuse, Transformer Protection, kV, E-Rated, Indicating, Bolt-In, 50kA, E ABrand: Mersen.
Back-up fuses are designed to protect only against high fault currents, and must be used in series with equipment which provides the circuit’s required overload and low value short-circuit protection. Medium Voltage (MV) “E-rated” fuses are considered general purpose liu-1.rug: christmas.
Mersen fuses for the protection of transformers and distribution lines deliver overload and short circuit protection. These current-limiting fuses will melt at current that can be as low as times the fuse current ratings up to its maximum interrupting rating. These fuses are designed to withstand the transformer magnetizing inrush liu-1.rug: christmas.
switchgear and transformer protection. Features and benefits • Current-limiting E-Rated medium voltage fuses are defined by their melting time-current characteristic that permit their electrical interchangeability with other fuses of the same E Rating.
• E-Rated fuses must have a defined current response time specified by ANSI CFile Size: 1MB. For over years, Bussmann fuses have provided superior circuit protection, enhanced safety and reliable service.
As the leaders in circuit protection, we’ve now expanded our medium voltage fuse portfolio to provide a fusible solution for virtually every medium voltage application with our current-limiting E-Rated, R-Rated and PT liu-1.rug: christmas.
undesirable, since the degree of transformer protection will be reduced, and coordination with the upstream protective device may be jeopardized. Also, since high- ampere-rated current-limiting fuses typically require the use of two or three lower-ampere-rated fuses con- nected in parallel, increased cost and space require- ments may be Missing: christmas.
The Coordinaide protection and coordination assistant software lets you quickly and easily select the optimal protective device (e.g., fuses, TripSaver II Cutout-Mounted Reclosers, Vista® Underground Distribution Switchgear, or IntelliRupter® PulseCloser® Fault Interrupters) to: Protect transformers against damaging overcurrents and coordinate with primary- and secondary-side protective Missing: christmas.
Cooper Bussmann low amperage, E-Rated fuses are designed to provide primary protection for potential, small service, and control transformers. These fuses offer a high level of fault current interruption in a self-contained non- venting package which can be mounted indoors or in an liu-1.rug: christmas.
2) Twin E fuses and 2-switches per phase. Some of the issues discuses are: a) Choose single fuse even if limit the maxi.
transformer near the top nameplate rating with limit emergency overloading. b) Oversize primary fuses to allow the operator to overload the equipment beyond the nameplate capacity under emergency liu-1.rug: christmas. Bussmann series Medium voltage ANSI / IEEE E Rated fuses. Our general purpose and full range E-Rated, current-limiting medium voltage fuses are designed for feeder circuit, switchgear and transformer protection.
Construction types include ferrule, bolt-on and clip lock, with special application fuses available for use with AMPGARD® motor starters. The ferrule fuses are available Missing: christmas. E-Rated (Full Range) MV 5EE, MV 5EE kV & kV, IR: 50,AIR ac See description for “E-Rated Transformer & Feeder Protection” fuses. Satisfies additional ANSI C for full-range protection fuse. A full-range fuse is capable of interrupting all currents from the rated interrupting rating down to the minimum continu-Missing: christmas.
E-RATED MEDIUM VOLTAGE FUSES Description E-rated fuses have time current characteristics designed to provide current-limiting protection for power transformers, potential transformers, power centers, feeder centers, and unit sub stations. When properly applied, they can protect against high and low fault liu-1.rug: christmas.
Transformer Protection Basics © Littelfuse POWR-GARD®Products liu-1.ru Transformers Rated Volts and Less. UL Industrial Control Standards (No. ) and Motor Control Center Standards (No. ) specify control power transformer protection corresponding to NEC Article (C).Missing: christmas. of Ferraz Shawmut E-rated fuses allows them to be closely sized to transformer full-load rated current, as recommended by IEEE guidelines, without being affected by normal magnetizing inrush current.
CS-3 fuses are typically sized at transformer rated current of %, thereby providing superior overall protection. APPLICATIOnS: Protection for ,Missing: christmas. The type of low voltage fuse for each distribution transformer depends on the low voltage conductor and the capacity of the transformer.
Bolt-in fuse links to BS88 are used on larger transformers supplying open wire LV systems, DIN standard fuses are typically Missing: christmas.
• NEMA Standards for R-rated MV power fuses require that fuses open within seconds when subjected to an RMS current times the “R” rating.
These values establish one point on the fuse’s time-current curve and help to define the overall performance characteristics of E- and R-rated fuses.
Since all E- and R-rated fuses must meet Missing: christmas. RTE Fuses ELSP Current limiting back-up fuse GENERAL The Cooper Power Systems ELSP Current-limiting Backup Fuse is used in series with low current primary protection devices such as a Bay-O-Net Fuse or MagneX Interrupter.
The ELSP fuse is designed for use in transformer oil, Envirotemp FR3 fluid, or an approved liu-1.ru fuse's highly efficient currentlimiting section minimizes the Missing: christmas.
All fuse ratings A and less are type X fuse links. All fuse ratings 7, 10, and 15 A are type X or type KS fuse links. All fuse ratings 20 A and larger are type KS fuse links. Fuse link ratings recommended in these tables will carry the full load of the transformer continuously and will open in five minutes when the transformer load isMissing: christmas. PT fuses are applied in industrial installations and commercial buildings for Potential Transformer and Control Power Transformer protection.
Definitions. E-rating: Over E must melt in seconds (10 minutes) on to % of E (ampere) liu-1.rug: christmas. E-Rated fuses have time current characteristics designed to provide current limiting protection for power transformers, potential transformers, power centers, feeder centers, and unit sub stations.
When properly applied, E-rated fuses can protect against high and low value fault liu-1.rug: christmas. Eaton’s Cooper Power series Bay-O-Net fuse offers a protection package for single- and three-phase transformers.
The assembly combines the ease of hotstick operation with the safety of deadfront construction and is used with an isolation link to prevent line personnel from closing into a fault when replacing a blown Bay-O-Net link. Eaton’s Cooper Power series MagneX Interrupter is an Missing: christmas. Electronic fuses are classified as either subminiature or miniature type fuses. The subminiature fuse category includes the Pico Fuse, the Micro Fuse, the x 8mm cartridge fuse, the x10mm cartridge fuse and the surface mount fuse.
A surface mount fuse is a subminiature fuse that is soldered directly on to a printed circuit liu-1.rug: christmas. Bussmann™ series E-Rated, current-limiting, medium voltage fuses for feeder circuit, switchgear and transformer protection. Features and benefits • Current-limiting E-Rated medium voltage fuses are defined by their melting time-current characteristic that permit their electrical interchangeability with other fuses of the same E liu-1.rug: christmas.
When applying fuses for the protection of transformers, the magnetizing current inrush must be considered. The characteristics of the inrush, which can be matched with a fuse’s time-current curve, should be available from the transformer manufacturer.
Fuse Type: E-Rated, Potential Transformer, R-Rated E-Rated. Indicating: liu-1.rug: christmas. E-Rated medium voltage fuses kV - kV Our general purpose and full range E-Rated, current-limiting medium voltage fuses are designed for feeder circuit, switchgear and transformer protection. Construction types include ferrule, bolt-on and clip lock, with special application fuses available for use with AMPGARD ® motor starters.
The ferrule fuses are available in aMissing: christmas. E-Rated fuses are used to protect feeder circuits, power transformers and potential transformers. E-Rated fuses have defined current response times specified by ANSI C E-Rated fuses A and below must melt in sec at an rms current within the range of % to % of the continuous current rating.
E-Rated fuses above A mustMissing: christmas. The Circuit Protection Specialist To Place International Orders Please Call: · Point 2: 12 x rated transformer current at s (transformer inrush) Point 3: 6 x rated transformer current at s (cold load pick-up) Point 4: 3 x rated transformer current at 10 s (cold load pick-up) Fuse Curve Selection for CSP Transformers W hend sig a CSP pr o tcm, l secondary CSP circuit breaker first in accordance with the protection Missing: christmas.
· Calculate Size of Circuit Breaker or Fuse on Primary and Secondary side of Transformer having following Detail Transformer Details(P)= KVA Primary Voltage (Vp)= Volt Secondary Voltage (Vs)= Volt Transformer Impedance= 5% Transformer Connection = Delta / Star Transformer is in unsupervised condition. Calculations: Transformer Primary Current (Ip)= P/xVp Transformer Missing: christmas. The PT fuse is used to protect the primary windings of a potential transformer or control power transformers (CPT).
A PT fuse is a small dimension ferrule type fuse that mounts in standard clips. Blown fuse indication is available on some PT fuse series. Potential Transformer fuse voltage ratings are from kV to kV. Potential Missing: christmas. The maximum interrupting rating for the kV fuse, 80 A through A at kV is 43 kA. For the 23 kV, A fuse (parallel A) the maximum interrupting rating is 12 kA.
① Parallel fuses ( A, 38 kV rated fuse consists of two A, 38 kV fuses (P/N CBUCD) in liu-1.rug: christmas. interrupting current.” The minimum rated interrupting current is the lowest current that the fuse will be able to clear properly. This creates a need to place a low current interrupting device in series with the back-up rated fuse. Catalog Symbol:ECL Description: E-Rated medium voltage, current-limiting fuses for transformer and feeder Missing: christmas.
· I'm pretty sure you are not supposed to fuse the secondary side of a transformer. The protection, if any, should be on the high voltage side, where the current is low.PM # varmit. Senior Member. Join Date: Apr Depending on the VA or KVA rating you may be required to fuse the primary and secondary. I don't have my Missing: christmas. · Fitting a Vac plug and cord to a toroidal power transformer is a bit tricky. As it is just a bare transformer, you '''must''' add a suitably rated fuse (check data sheet for value) inline with the Active wire.
The Neutral and fused side of the Active wires go to the "primary" side of the transformer. Medium voltage current limiting and expulsion fuses suitable for the protection of distribution transformers, voltage transformers, capacitor banks, motor circuits and installations with other switching apparatus.
Key benefits. Capable to control full range of overload currents either in combination with switching apparatus or as sole protectionMissing: christmas. In-line fuses provide in-line circuit protection for fluorescent lighting fixtures. SFE fuses are 32 volt glass cartridge fuses that vary in length depending on the ampere rating.
Barrier Network fuses are axial leaded cartridge fuses that are designed to safely operate in potentially explosive environments. The Safe-T-Plus is an encapsulated Missing: christmas. protection per the transformer through-fault protection curve defined in ANSI standards for a broad range of secondary-side fault currents.
The life-shortening thermal and mechanical stresses associated with prolonged transformer through-faults are minimized. SMD Power Fuses are ideal for protection of auxiliary (station service Missing: christmas. Mersen 9F60 Transformer Protection Power Distribution E-Rated Fuse with Ferrule Mount, kV, 50kA, E Ampere, 3" Diameter x /8" Length Currently unavailable.
We don't know when or if this item will be back in stock. Specifications for this item. Brand Name: Mersen Ean: Item Diameter: 3 inches Missing: christmas. · Typically, the fuse will cross the transformer damage curve in the long time region (overcurrent region). The secondary main device provides overcurrent protection for the circuit. “E” fuse ratings should always be greater than the transformer full load amps (FLA).
The cable damage curve must be above the maximum fault current at liu-1.rug: christmas. For transformers with an IFD, PG&E has modified its procedure so, if the IFD indicates a fault, the lineman always changes out the transformer regardless of the number of fuse operations. If the IFD does not indicate a failure, then even if two or three fuses have blown, it is fine to install new fuses and try the liu-1.rug: christmas. 3 Transformer Circuit Fuses (N.E.C.
b, d, b Ex. 3, 4 & (c) as required):* a) PRIMARY FUSES: Size fuses not over motor nameplate current rating. b) Best protection is obtained by measuring motor running current and sizing fuses at % of measured current for normal motor operation. ReferenceMissing: christmas. The second stipulation pertains to overcurrent protection. In accordance with (D)(1)(2), overcurrent protection shall be provided by one of the following: 1.
branch-circuit-rated circuit breakers listed and marked for use with 18 AWG copper wire; 2. branch-circuit-rated fuses listed and marked for use with 18 AWG copper wire; or liu-1.rug: christmas. Cooper M01M E Rated Transformer Protection Fuses ELSG Fuse, kv. New - Open Box: A new, unused item with no signs of wear. The item has its original packaging but it is not sealed. E-Rated Medium Voltage Fuses: ECL For Transformer and Feeder Protection CL kV Form No.
ECL Page 1 of 4 Data Sheet: Bussmann ® CATALOG SYMBOL:ECL E-RATED MEDIUM VOLTAGE FUSES: Meets E requirements per ANSI C Meets General Purpose requirements per ANSI C FOR TRANSFORMER AND FEEDER PROTECTION VOLTAGE RATING.
E-Rated fuses are general purpose fuses that operate: E or less must melt in seconds at to percent of E rating. Over E must melt in seconds at to percent of E rating. Example: A E fuse must melt in seconds with an applied current of to amperes.
These fuses were designed and originally tested at a. E-rated medium voltage fuses are general purpose fuses that are primarily used to protect transformers and provide both current overload and short circuit protection.
R-Rated fuses are back-up fuses primarily used to protect motors and motor controllers. R-Rated fuses only provide short circuit protection. Superior transformer protection. You can fuse close to the transformer full-load current and thus protect against a broad range of secondary-side faults.
Higher levels of service continuity. “Sneakouts” (unnecessary fuse operations) are eliminated. Close coordination with other protective devices. · e.g. This article explained the selection of FUSE rating, CB rating only.
it doesn;t explain the protection setting (Pick Up point for Inst and IDMT). If there any article for Overcurrent Protection for transformer Setting (Instantaneous and IDMT), please share. SYSTEM PROTECTION – FUSING IV. 7 - Page 1 of 8 SYSTEM PROTECTION FUSE COORDINATION AND TRANSFORMER FUSING INTRODUCTION 1. The purpose of protective coordination is to provide isolation of a fault as close to the fault as possible so that a minimum of customers will be affected. The workhorse of the JEA protection scheme is the fuse.
This set of protections is used on HV and MV transformers with rated power above MVA as a “back-up” protection, in addition to the differential protection. In some installations and networks MV transformers with rated power up to kVA may be protected against overcurrents by fuses associated to switch-disconnectors, as shown in.
Transformer Protection Application Guide This guide focuses primarily on application of protective relays for the protection of power transformers, with an emphasis on the most prevalent protection schemes and transformers.
Principles are emphasized. Setting procedures are only discussed in a general nature in the material to follow. b. Circuit breaker size or fuse rating up to % of transformer-rated current, for transformers with secondary voltage 1,V or less.
For transformers with primary voltage 1,V or less and current of 9A or more, with primary protection not more than % of transformer-rated current, the “next-size-up” rule can be applied [Table (B)]. JOE E-Rated Current-Limiting Power Fuses: GENERAL The Cooper Power Systems JOE current-limiting power fuses are E-Rated per IEEE Std C™ standard, providing an excellent choice for protection of transformers, feeder circuits, high voltage switchgear, and metal-enclosed switchgear.
Voltage ratings include kV and kV. · Differential Protection of Transformer. The Percentage Biased Current Differential Protection is used to protect power transformers and it is one of the most common transformer protection schemes that provide the best overall protection. These types of protection are used for transformers of rating exceeding 2 MVA. · Figure 1 – HRC fuses. Go back to contents ↑ Overcurrent relays. With the advent of ring main units incorporating SF6 circuit breakers and isolators, protection of distribution transformers can now be provided by overcurrent trips.
For example, tripping controlled by time limit fuses connected across the secondary windings of in-built current transformers) or by relays connected to. Mersen fuses for the protection of transformers and distribution lines deliver overload and short circuit protection.
These current-limiting fuses will melt at current that can be as low as times the fuse current ratings up to its maximum interrupting rating. These fuses are designed to withstand the transformer magnetizing inrush current. Fuse Transformer Protection kV E-Rated Indicating Clip-Lock Mount 63kA 15E A. Allied Stock #: Mfr's Part #: AC1D0RE. $ Each. Quantity added: Don't show this to me again and take me directly to the cart.
You'll still have a chance to review your order. On the surface fuses as protection for transformers are a poor construction. It is the operating temperature in the windings that determines the permitted load. A transformer can be severely overloaded for brief peri-ods, e.g. in the case of contactor making, which can be many times the power of the transformer.
The transformer primary fuse should be selected to pro-vide both system and transformer protection. With respect to system protection, the primary fuse should detect a potentially damaging overcurrent condition and operate promptly to isolate only the faulted segment, thereby mini-mizing short-circuit stresses on the remainder of the sys.
Overcurrent Protection of Transformer (NEC ) This technical article written by same author mr. Jignesh Parmar explains step by step NEC (Transformer protection). Introduction; Overcurrent protection of transformers >V (NECA) Unsupervised location of transformer (impedance transformer (impedance 6.
Mersen Amp-Trap Bolt-In Transformer Protection E-Rated Fuse, kV, 63kA, 15E Ampere, /4" Length x /8" Width: liu-1.ru: Industrial & Scientific Skip to main content Try Prime. · Greetings, I am trying to determine how to size a set of primary fuses in a load break switch which will be feeding (3) loop fed KVA transformers. It is considered an unsupervised location. NEC tells me maximum % of transformers rated current but that would be for a single transformer.
Limit Amp Style Bolt-in R-rated Motor Starter Fuses are current-limiting, high interrupting rating fuses intended for the short-circuit protection of General Electric Limit amp brand of medium voltage motors and motor controllers. · For the common delta-wye connected transformer, a fusing ratio of would provide backup protection for a phase-to-ground fault as low as % of the secondary full-load rating.
Fusing ratio is defined as the ratio of the fuse rating to the transformer full load current rating. Fuses with utilization category gG are matched in their time/current characteristics to the maximum permissible load of insulated cables.
gG fuses also protect electrical systems and devices and can be employed for backup protection of components such as residual current circuit-breakers, miniature circuit-breakers and molded case circuit breakers. transformers, etc. BREAKING CAPACITY: Also known as interrupting rating or short circuit rating, this is the maximum approved current which the fuse can safely break at rated voltage.
Please refer to the INTERRUPTING RATING definition of this section for additional information. CURRENT RATING: The nominal amperage value of the fuse.
· tive devices such as fuses and circuit breakers may be required to safely open (interrupt). Although there are differences in the way fuses and circuit breakers are tested, the Interrupting Rating or Interrupting Capacity of a fuse or circuit breaker is assumed to be its SCCR. Article of the NEC requires overcurrent protective devices. The range of fuses have pre-arcing I2t values towards the bottom limits of BS 88 Parts 2 and 6.
This ensures excellent current and energy limitation. They also have lower power losses at rated current. This assists in the appropriate interchangeability with other makes of fuses. Transformers When fuses are used on the primary side of transformers. 2. In the case of transformer fuses, the degree of overcurrent protection to be provided.
3. Load current at the point of application. 4. The fault current available at various locations on the system. 5. Time current characteristics of fuse links to be used on the system. 6. The type of protection to be provided by the fuse. protection for a transformer winding 38 ‘63’ protection against internal anomalies for oil transformers (Bucholz relay) 39 ‘26’ overtemperature protection 39 ‘51G’ tank protection 39 Protections for motors 40 ‘49’ thermal image protection against.
Bussmann™ series E-Rated, current-limiting, medium voltage fuses for feeder circuit, switchgear and transformer protection. Features and benefits • Current-limiting E-Rated medium voltage fuses are defined by their melting time-current characteristic that permit their electrical interchangeability with other fuses of the same E Rating. of the fuse, e.g. inside the moulded plastic container, and the resulting limited dissipation of heat losses as com-pared to fuses in air, the rated operating current of the device combination is below the rated operating current of the fuse Ir-HV HRC.
This means that the device combina-tion cannot be loaded with the full rated fuse current. OUTPUT FUSE = 1*% next size higher if secondary current is 9 Amps or higher. Recommended fuse size per NEC[B] and commercially available fuse types. Primary General Purpose Transformers Secondary General Purpose Transformers VA 3K 12 (20) 9 () 5 (9) 4 (7) 12 9 6 5 6K 25 (40) 20 (35) 9 (15) 8 (12) The second stipulation pertains to overcurrent protection. In accordance with (D)(1)(2), overcurrent protection shall be provided by one of the following: 1.
branch-circuit-rated circuit breakers listed and marked for use with 18 AWG copper wire; 2. branch-circuit-rated fuses listed and marked for use with 18 AWG copper wire; or 3. using an AC only fuse in a DC circuit could result in violent destruction of the fuse.
The standard volt rated fuses discussed in this section may be applied at any voltage less than or equal to their rating. For example, a volt fuse may be used in a volt or even a 32 volt system, but not any system exceeding volts.
In the US, roughly most standard fuses and breaker are rated at % of current--Fuse/Breaker will eventually trip; at ~80% of rated current, the breaker/fuse should not trip. So, if you have a system rated at Amps maximum charging current, then you should up size the wiring/fuses/breakers by 1/ or times or A*= amps minimum. Current Limiting Fuses Hi-Tech current limiting fuses Hi-Tech is an industry-leading brand of current-limiting fuses with advanced designs to provide maximum protection in small, cost-efficient form factors to optimize value.
1. If a V main class L fuse is used with a rating on the order of % of the transformer rating, the incident energy for faults on the main bus will be > cal/cm2. 2. If a main V breaker is used with a long time pick up (LTPU) on the order of % of the transformer rating, a short time pickup (STPU) in the range of 2 to 3. In general, transformers between 75VA and VA are reasonably easy to protect, both against a catastrophic failure or sustained overload, although even these can be affected by significant power-on inrush current (~VA and above).
A slow blow fuse of the appropriate rating usually offers the best protection at the lowest cost. Return High and Medium Voltage Fuses and Fuse Bases. E Rated General Purpose Medium Voltage Fuses; R Rated Back-Up Medium Voltage Fuses; Potential Transformers Protection Fuses; HV & MV Fuse Bases; Capacitor Protection Fuses; DIN HV Back-Up Fuses for Motors; DIN HV Back-Up Fuses for Transformers; DIN HV General Purpose Fuses for Transformers.
· This section covers transformer ratings (i.e. voltage, primary BIL) and Line Numbers. Three phase pad mount transformers specified in this Section shall be supplied with isolated primary taps.
Refer to Table in Section for t ap changer identifications and positions. H.V. current-limiting fuses type S is mainly used in AC50Hz, rated voltage kV, rated current up to A circuit for protection transformers and power equipment’s from overload and short-circuit. It can also be used with load switch, vacuum contact.
It conforms to IEC, GB and DIN standard. Design Features. The innovative and comprehensive range of Mersen fuse-holders. CCR fuse-holders are finger-safe under IEC standards to an IP20 grade of protection, including fuse changing (with the flick of a finger).
CCR fuse-holders are available in 1, 2, 3 poles, in IEC version in a very special compact design. · Control circuit fuses have a variety of different voltage ratings, ranging from 32 V to V, and interrupting ratings up to kA. As the physical size of these fuses does not vary with voltage or interrupting rating, the most common cause of misapplication is due to improper voltage or interrupting rating.
Similar to feeder taps, covered in the last issue, transformer secondary conductors can be every bit as confusing. Let's take a closer look at (C) to help clear up any misconceptions.
Basic rules As with feeder taps, you can't use the rule provided in (B) for any transformer secondary conductor. Normally, you can use the next highest overcurrent protective device (OCPD) above the. · = 40 °C and at rated values, if nothing else indicated Main circuit 1LLL3 2TTT3 Rated operational voltage U e V AC-Setting range - thermal overload protection see table “Order data” on page 1 Rated operational current I e see table below Rated operational current DC-5 I e 3 conducting paths in series up to V.
The short-circuit power factors are relatively high: to for fuses rated A to A, and to for fuses rated A and less. The actual short-circuit power factors encountered in typical installations are on the order of the above test values, when the available short-circuit current is 10kA rms symmetrical or less.
up to thirteen different fuse curve variations. The three voltage classes are 15 kV, 23 kV, and 35 kV. These ratings apply to a single phase transformer’s line to ground voltage, or a three phase transformer’s line to line voltage.
For example, a three phase transformer connected to. Defines the range of amperage ratings for your search results. To search by a single amperage rating, select the same amperage in each field.
For R-Rated fuses, the “R” designation does not match the rated current e.g., 2R = 70A. · Low-voltage distribution systems use fuses rated from 20 A through 6, A. Medium-voltage distribution systems are limited to A fuses (twin E fuses derated to E).
Above A, the engineer must specify breakers instead of fuses.