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Maryland Metrics: SIBA fuse glossary

   
Ambient Temperature Temperature of air, measured in a 1 m distance of the fuse. Fuses are normally built for
  surrounding temperatures of -5 to +40 °C. Higher or lower temperatures may influence
  the Time/Current-Performance. Time/Current-Characteristic refers to a temperature
  between 20 to 30 °C.
   
Arc Quenching Time As part of the Operating Time this is the time between the arc starting and the final current
  zero. Depending on the Melting Time the Arc Quenching Time is just a few ms up to a
  couple of 100 ms.
   
Arc Voltage Highest voltage, which is measurable during the Operating Time of the fuse measured at
  their contacts. Mostly 2 or 3 times or the Rated Voltage will be reached. In power electronic
  circuits this value must be compared to the one of the semiconductor.
   
Arcing withstand Time Longest time between separation of the melting element and the faultless interruption of
  the failure current through the fuse-switch. Value is needed for comparison to the
  fuse-initiated opening time of the switch. The opening time must be smaller than the Arc
  Remaining Time. The values are mostly above 100 ms.
   
Back-up Fuse Cut-off-current Fuse, which is able to operate between the Minimum Breaking Current and
  the Rated Breaking Current. For protection of transformers, capacitors and motors.
   
Center Indicator Typical indicator for square body semiconductor protection fuses. It consists of an adaptor
  for the fuse and microswitch. The microswitch is offered as a separate part. For fuse-links
  with centre indicator the corresponding adaptor must be mounted on the insulating body.
   
Characteristic Information of the breaking range and of the usage of the fuse. Typical Characteristics are:
  gG, aM, gM, aR, gR, gTr, gB. Quick acting, Time lag, Time-lag/Quick-acting, gL, gI, gII are
  terms as invalid standard or company standard.
   
Characteristic aM Characteristic of a back-up fuse-link for motor circuit protection. Fuse is intended to be
  used for protection of cable short-circuit. Overloads have to be considered with other
  appliance.
   
Characteristic aR Characteristic of a back-up fuse-link for semiconductor protection. Fuse link is intended to
  be used for short-circuits. Overloads have to be considered with other appliance.
   
Characteristic gB Characteristic of a general purpose fuse-link for protection in mining installations. Fuse
  with quick-acting Characteristic at short-circuits.
   
Characteristic gG Characteristic of a general-purpose fuse-link for general installations. Protection of lines,
  transformers, motor-circuits and capacitors. The old term of that Fuse-link is "gL".
   
Characteristic gL Old name for the characteristic of a general-purpose fuse-link for general installation.
  New name: gG.
   
Characteristic gR Characteristic of a general-purpose fuse-link for semiconductor protection. Mostly for
  Rated Current Range < 100 A.
   
Characteristic gRL Characteristic of a general-purpose fuse-link for the protection of semiconductors and
  their feed lines. New combination protection that supersedes the former additionally used
  gG fuse-link inside the lines. (See the technical essay at our web-site)
   
Characteristic gTr Characteristic of a general-purpose fuse-link for overload protection of power
  transformers as short-circuit protection for low-voltage bus bars. These fuses are
  designed to a discrimination of the high-voltage fuses.
   
Conventional Time Given time within the fuse-link must operate (Fusing Current) respectively not operate
  (Non fusing Current) under defined conditions. The Conventional Time depends on a
  given Rated Current range. The time varies between 1 and 4 hours.
   
Current Gate Limiting value in the Time/Current-Range of the fuse. Minimum and maximum of Rated
  Currents within a given time.
   
Cut-off Current In case of short-circuit the maximum value of the short circuit current, which loads the
  installation or the protection gear. This value is required for the analysis of the dynamic
  impacts of the short-circuit current to the installation or the gear.
   
Derating Term for any kind of reduction influences on the Rated Breaking Current of the fuse. The
  Derating value is multiplied with the Rated Current or to divided by the loading current. In
  some cases some influencing factors have to be considered, typically, high surrounding
  temperature, Terminal cross section, installation volume, pulse load, shock load and
  over-waves.
   
Discrimination Classification of relevant parameters (Time/Current-Characteristic; Integrals; Operating
  Times etc.) of two or more overload protection devices to each other. In case of overloads
  only the protection device should react. Fuses with the same characteristic are mostly
  selective to each other, if they are selected in the proportion 1:1,6. That means, that a fuse
  with a rated current of 100 A should be downstream of a fuse rated 160 A. For the
  short-circuit range the comparison of the melting integrals versus the Operating integral of
  the downstream fuse is important.
   
Fuse Element Part of the Fuse-Link, which melts while switching off the fuse. It consists mostly of
  perforated metal stripes. The dimension of the perforation reflects the Characteristic and
  the Rated Current of the Fuse-Link. Depending on the Rated Current the Fuse-Links
  contain several paralleled Fuse Elements. Typical materials are copper and pure silver.
   
Fuse initiated opening time Time between separating of the melting elements and the faultless interruption of the
of the Switch failure current through the fuse-switch. Values mostly between 30 and 100 ms.
   
Fusing Current Determined value of the current, which will be interrupted within a given time of the fuse.
  Valid for general purpose fuse-links, e.g. gG-fuses. Normally the testing current is about
  1,6 times the Rated Current.
   
General Purpose Fuse A current limiting fuse, which interrupts most of the melting currents under certain
  conditions. From the Fuse Rated Current up to the current which leads to a time <= 1h for
  interrupting the fuse-link. Melting Current of a Melting Time of 1 h is mostly between 1,5
  and 2 times the Rated Current.
   
General Purpose Fuse-link Current limiting fuse, which melting elements melt under determined conditions for
  usage and current performance until the Rated Breaking Current.
   
HHM Design of a SIBA-DIN-High-Voltage Fuse for motor circuit application with low heating and
  quick-acting short circuit performance. MCA-Fuses are also available in British sizes.
   
Homogeneous Series A series of fuse-links with basically the same size and material of the main range, but with
  different melting element dimensions. Contacts, bodies and the pattern on the melting
  element are identical. Although thickness or widths of the melting elements vary, the
  number depends on the rated current.
   
Indication Switch for Indication switch is fixed on the removal tags of a low-voltage fuse-link and is triggered by
Removal Tags the cover plate indicator. The contacts of the switch are mostly for 250 V and up to 6 A. A
  reliable means to giving remote indication of the operating status of the fuse.
   
Indicator Appliance which shows the operating status of the fuse-link. It is mostly on, or in the
  contact cap, cover plate or in the middle of the insulating body of the fuse-link. The
  combination indicator of the SIBA Low voltage fuse-link which combines cover plate
  indicator and centre indicator provides a reliable visible indication.
   
KS-Fuses SIBA-Sub miniature-Fuse according IEC 127-3 respectively VDE 0820-3. Available on
  taped reel for automated assembly.
   
Melting Current Current during an increase in prospective Short-Circuit Current, at which the Fuse
  Element melts. This current is usually lower than the Cut-off Current, because this
  normally increases during the Quenching Time.
   
Melting Integral Current Integral for the Melting time of the fuse. The Melting Integral depends on the size
  of the Melting Elements and is therefore independent from voltage. The data sheet
  normally contains the minimum value, which is used for analysing discrimation.
   
Melting Time Time period from the beginning of the failure current to the melting of the fuse elements.
  The Time/Current-Characteristic shows the virtual Melting Time. It considers different
  curves and closing angles of the current. Virtual Melting Time = Melting Integral / failure
  current˛.
   
Minimum Breaking Current Smallest failure current at which a back-up fuse can operate at its rated voltage. Values
  are often between 3- and 4- times of the Rated Current.
   
Non fusing Current Defined value of current, at which (under certain circumstances) a fuse- link must not
  operate within a given time (Conventional Time). For General Purpose, e.g. gG-Fuse. This
  value is normally 1,25 times the Rated Current.
   
Operating Integral Current integral over the operating time of the fuse. General information is mostly valid for
  melting times less than 5ms. That means the fuse has operated with current limitation.
  Usually is the value shown in the data sheet as the highest one to expect for the given
  reference voltage. Values at lower service voltage are calculated through the conversion
  diagram.
   
Operating Time Summation of Melting Time and Arc Quenching Time of the Fuse. Over a Melting Time of
  100 ms the Operating Time can generally be equated with the Melting Time. For shorter
  Melting Times the Operating Time can be more than double of the Melting Time. Below 5
  ms the Operating Time should be counted back through the Operating Integral.
   
Power Acceptance Highest value of released energy in a fuse-link a holder or a base can be loaded with
  under certain conditions. In case of mounting several fuse- bases eventually reduction
  factors have to be considered.
   
Power Dissipation Power loss during the load of a fuse-link with the Rated Current under certain conditions.
  The given values in the catalogues may vary distinct from the measured values, because
  different installation conditions are influencing the power loss.
   
Prospective Current Current in an installation if the fuse is of negligible resistance, because of a bridging.
  RMS value of the short-circuit current, which is terminated through the fuse on a maximum
  value (Cut-off Current).
   
Rated Breaking Capacity Capacity of a fuse to operate between the lowest and the Rated Breaking Current. The
(Low-/High-Voltage Fuses) Rated Breaking Current is an effective value. The laboratory, where the fuses are certified,
  gives the maximum of the Breaking Current. Normally the fuses can operate higher
  currents. Typical values for Low-Voltage are: 100, 120, 200 or 300 kA; for High-Voltage 20 -
  63 kA.
   
Rated Breaking Capacity Current, at which a fuse can operate normally under determined conditions at a fixed
(Miniature Fuses) Voltage. Classified as the letter 'L' for low, 'E' for middle and 'H' for high Breaking Capacity.
   
Rated Current Current that a fuse can run continuously without operating. The current was determined at
  standardized conditions. That means the fuse was in free air with defined cable
  cross-sections. The feed line of 1m length was displaced openly. Often the Rated Current
  has to be reduced by the Derating-value.
   
Rated Frequency For the first certification based frequency. Generally the fuses are for a net-frequency at 45
  - 62 Hz. The usage for lower or higher frequencies should be discussed with SIBA.
   
Rated Voltage Effective value of the Operating Voltage of a fuse; normally alternating voltage. Information
  is valid for Operating Voltage between 42 - 62 Hz. Track Power Supply (16 2/3 Hz) need
  fuse-links of the next highest voltage series.
   
Recovery Voltage Value of the voltage at the contacts after operating of the fuse. Mostly similar to the
  load-voltage.
   
Remote Indicator A special model range of Low-Voltage Fuses have a signal indicator. It operates on a fuse
  base mounted micro-switch if a fuse operates. Design is often used in safety sensitive
  applications.
   
Resistance Given in the data sheet at an ambient temperature of 20 °C.
   
Retaining Force Former name for the energy when the striker pin of a high-voltage fuse operates. Typical
  values of the Retaining Force for SIBA-DIN-Fuses are 80 N. Another design has got 120 N.
   
SSK-Type Type of SIBA-DIN-High-Voltage Fuse, which is designed for switchgear with low ratings for
  the fuse-initiated opening times and small take-over currents. Under certain conditions it
  increases the application possibilities of switch/fuse combination to bigger transformers.
  (See the technical essay on our web-site)
   
Striker Pin Part of the High-Voltage Fuse, which gives on the one hand the information „operated“ or
  „still working“. On the other hand it gives through the pressure spring the necessary
  energy to open other switches or cause an interlock. Depending on the release energy the
  striker pins are classified in 'light', 'medium' and 'heavy'. DIN-High-Voltage Fuses are
  provided with a medium striker pin.
   
Switching Voltage Highest value of the voltage, which is measurable at the contacts during the Operating
  Time of the fuse. It has mostly 2-3 times of the Rated Voltage. In power electronic circuits
  this value must be compared to the one of the semiconductor.
   
Take-Over Current Take-Over Current at operating the Striker Pin: Value of the symmetrical three phase
  current at which the breaking varies between the fuse and the switch. Directly below this
  value the current will be interrupted in the first quenching pole through a fuse and the
  current in both other poles through the switch. Above these values the current will be
  interrupted in all 3 poles only through the fuses. Depending on the Rated Voltage of the
  switch the values are mostly between 600 and 3000 A.
   
Temperature Limiting Striker Pin of SIBA-DIN-High-Voltage Fuse with two functions: indication and triggering
Striker Pin while the fuse operates. Especially when used in gas-isolated switchgear with narrow
  fuse mounting canisters, the Temperature Limiter gives reliable protection in case of
  heating by operation of the striker pin. Since 1994 all SIBA-DIN-Fuses with Rated Currents
  up to and including 160 A are provided with the temperature limiting striker pin. (See the
  technical essay at on web-site)
   
Time/Current-Characteristic For Miniature Fuses: Characteristic to calculate the Melting Time of the fuse under given
  overload and respectively short-circuit currents. Time/Current Characteristic refers to the
  Melting Time and Operating Time. Symbols used: FF very quick acting, F quick-acting, M
  medium time lag, T time lag and TT super time lag.
   
Time/Current-Curve Curve for calculating the Melting Time of the fuse at target overload and respectively
  short-circuit current. Time/Current-Curves refer to a temperature between 20 and 30 °C
  and are given at times between 0,004 and 10000 s. They are drawn in a double
  logarithmic grid pattern.
   
UMF-Fuse Sub miniature Fuse for direct mounting on circuit boards in SMD-Technique or with solder
  pins according IEC 60 127-4 and VDE 0820-4. Worldwide similar characteristic different to
  sub miniature fuses.
   
Virtual Melting time Standardised value of melting time, which considers currents of types AC or DC and the
  different current curves and switching angles. The Melting Time in the
  Time/Current-Characteristics is generally given by the Virtual Melting Time. The value is
  calculated by the Melting integral of the Rated Current.
   
VS-Protection SIBA-VS Type is a General-Purpose fuse in DIN design. Under certain conditions this fuse
  interrupts all currents from a Rated Current to the current which leads to a melting time of
  <= 1h. The Melting Current at a Melting Time of 1 h mostly reaches values between 1,5
  and 2 times of the Rated Current.

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