Eska Fuses and Circuit Protection Components

Eska fuses and passive circuit protection devices for industrial electronics, automation, power systems and e-mobility: technical selection by six-digit part number and circuit ratings.

Eska 5×20 mm cylindrical cartridge fuses: 520, 521, 522 and 528 series

Miniature appliance protection fuse-links in the 5×20 mm format designed to IEC 60127-2 with glass and ceramic bodies for industrial power units, programmable controllers and drive boards. Available with nickel-plated brass end caps or axial wire leads for through-hole assembly.

Very quick-acting and quick-acting series 520.000, 520.100, 520.500 and 520.600 up to 20 A
Medium time-lag series 521.000, 521.500 and indicator striker version 528.100
Time-lag and long time-lag series 522.000, 522.400, 522.500, 522.600 and 522.700
Rated voltage 250 V AC/DC and breaking capacity from 35 A up to 1,500 A depending on model

Eska 6.3×32 mm, multimeter and extended cylindrical fuses: 632 and 1038 series

Cylindrical fuse-links in the 6.3×32 mm format (632 series), 10.3×38 mm multimeter protection fuses and extended sizes from 5×15 mm to 8×150 mm engineered for power electronics, laboratory instrumentation, frequency converters and switchgear cabinets.

Series 632.000, 632.100, 632.200, 632.300, 632.400, 632.600 and 632.900 rated 100 mA to 25 A
Operating voltages from 250 V to 500 V AC/DC with breaking capacities up to 1,500 A
Five time-current characteristics (FF, F, M, T and TT) matched to inductive or resistive loads
Special dimensions 5×15, 5×25, 5×30, 8×40, 8×50, 8×85, 8×120, 8×150 and 10.3×38 mm

Eska sub-miniature and SMD/SMT chip fuses: 885, 887 and 0603–2410 packages

Compact circuit protection elements designed for high-density printed circuit boards in industrial automation, PLC I/O modules, telecommunication interfaces and LED drivers. Available in surface-mount chip packages and radial or axial through-hole housings.

Radial and axial sub-miniature series 883, 885 and 887 (887.117, 887.121, 887.123, 887.125)
Surface-mount SMD and SMT chip fuses in standardized 0603, 1206 and 2410 footprints
Fast-acting thin-film and ceramic types including FUSE 1206-FF PW and FUSE 0603-FF PW
Tape-and-reel or bulk packaging suited for automated pick-and-place lines and board repair

Eska resettable PPTC fuses and metal-oxide varistors (MOV) for surge protection

Polymeric positive temperature coefficient (PPTC) resettable protection elements and metal-oxide varistors (MOV) engineered to safeguard measurement buses, communication ports, servo drives and power supplies against overcurrent faults and transient voltage spikes.

Resettable PPTC fuses transitioning to a high-resistance state under overcurrent loads
Automatic circuit restoration once the overload condition is cleared and power is cycled
ESKA MOV metal-oxide varistors clamping switching surges and lightning-induced transients
Radial leaded discs and surface-mount packages for industrial input filtering stages

Eska thermal cutoffs (735–785) and bimetallic temperature switches (36T, TK24)

Thermal protection devices for electric motor windings, power transformers, HVAC heaters and industrial appliances: non-resettable axial and radial thermal cutoffs alongside auto-reset and manual-reset bimetallic temperature switches.

Axial and radial thermal cutoff series 735.000, 740.000, 750.000, 755.000 and 761.000
Series 770.000 (including 770.104), 771.000 and 776.000–785.000 rated 250 V AC / 24–60 V DC
Bimetallic temperature switches 36T (Auto Reset and Manual Reset) and TK24 series
Switching ratings for 120 V AC and 250 V AC heating, cooling and overtemperature circuits

Eska NH power fuses, photovoltaic, battery fuse-links and fuse holders

High-current and application-specific fuse-links for power distribution boards, solar photovoltaic arrays, battery energy storage systems (BESS) and industrial vehicles, complemented by panel, PCB and inline fuse holders and press-in contacts.

NH blade power fuse-links and PowerFuse series for industrial switchgear assemblies
Photovoltaic fuse-links (gPV) engineered for solar string and inverter DC protection
Battery Fuses and automotive series including 58 V DC ratings (343430-58V, 343439-58V, 343443-58V)
PCB, panel-mount and inline fuse holders, open clips and Einpresstechnik press-fit terminals

Decoding six-digit Eska part numbers and end-cap markings

The numbering system of ESKA Erich Schweizer GmbH is structured around six-digit numerical codes separated by a dot, where the first three digits define the series, physical dimension and time-current characteristic, while the last three digits specify the rated current and lead configuration.

For instance, prefixes 520.5xx and 520.6xx denote quick-acting 5×20 mm cartridge fuses, 521.0xx identifies medium time-lag models, and 522.5xx or 522.7xx indicate time-lag designs.

When inspecting a blown fuse-link, engineers read the stamped alphanumeric code on the nickel-plated brass end cap: the tripping curve letter (FF, F, M, T or TT), the current rating in milliamperes or amperes, the rated voltage (such as 250V) and the breaking capacity symbol (L for glass tube low breaking capacity or H for sand-filled ceramic tube high breaking capacity).

Selecting the time-current characteristic: FF, F, M, T and TT curves

Matching the tripping curve to the load profile avoids nuisance blowing during normal equipment start-up while protecting sensitive power electronics during short-circuit faults.

Very quick-acting (FF, superflink) and quick-acting (F, flink) fuse-links in the 520 and 632.100 series feature a low melting integral I²t and are selected to protect thyristors, triacs, IGBT modules, measurement shunts and PLC input channels.

Circuits experiencing substantial inrush currents—such as switched-mode power units with input filter capacitors, control transformers, solenoid valves and motor drives—require medium time-lag (M, series 521 and 632.200), time-lag (T, series 522 and 632.300) or long time-lag (TT, series 522.400) fuse-links engineered to withstand transient surge pulses without thermal fatigue.

Breaking capacity, AC/DC voltage ratings and body materials

Rated breaking capacity defines the maximum prospective fault current that a fuse-link can safely interrupt without rupturing its body or sustaining an electric arc.

Glass-body miniature fuse-links with low breaking capacity (L rating under IEC 60127-2) handle 35 A or 10 × In and provide clear visual inspection of the melting element in secondary control and instrumentation circuits.

Primary power feeds, industrial inverters and digital multimeters require ceramic-body fuse-links with high breaking capacity (H rating, up to 1,500 A at 250–500 V AC) filled with arc-quenching quartz sand.

For direct-current circuits—such as 24–60 V DC battery and telecom buses or 1,000–1,500 V DC solar photovoltaic strings—engineers verify the dedicated DC voltage and breaking rating in the datasheet.

Non-resettable thermal cutoffs versus bimetallic temperature switches

Within the Eska thermal protection portfolio, engineering teams distinguish between one-shot thermal cutoffs (series 735.000 to 785.000) and resettable bimetallic temperature switches (series 36T and TK24).

A thermal cutoff incorporates a temperature-sensitive pellet or alloy link that permanently opens the circuit once the rated functioning temperature Tf is exceeded, preventing fire hazards if a primary thermostat fails.

Bimetallic temperature switches 36T and TK24 utilize a snap-action bimetallic disc designed for repeated switching cycles at 120 V AC or 250 V AC.

Auto-reset variants reclose the contacts automatically once the assembly cools down to the reset temperature, whereas manual-reset models remain open until service personnel inspect the equipment and press the reset button.

PCB mounting configurations: SMD chips, radial THT leads and fuse holders

Selecting Eska circuit protection components for industrial electronic assemblies involves verifying both footprint geometry and thermal dissipation across the terminals.

Surface-mount chip fuses in 0603, 1206 and 2410 footprints require adherence to recommended land patterns and reflow soldering profiles so that thermal stress during assembly does not alter the pre-arcing characteristic.

Sub-miniature radial and axial fuse-links in the 885 and 887 series solder directly into through-hole boards with compact lead spacing, saving board area compared to cartridge clips.

When specifying panel-mount, PCB-mount or inline fuse holders and press-fit terminals (Einpresstechnik), engineers check the maximum rated power acceptance Pv and contact resistance.

How to prepare a technical inquiry for Eska fuses and passive components

For rapid identification, include the six-digit Eska article number (for example 520.625, 522.516, 632.625, 770.104 or 887.117) or the complete alphanumeric imprint from the metal end cap or package.

When replacing an unmarked component, specify the physical dimensions (5×20 mm, 6.3×32 mm, 10.3×38 mm, SMD 1206), rated current, AC/DC operating voltage, tripping curve (FF, F, M, T, TT) and tube material.

For thermal protection items, indicate the rated opening temperature in degrees Celsius, holding temperature, current rating, lead style (axial, radial or flanged 36T/TK24 housing) and reset mode.

We cross-reference the specifications against ESKA Erich Schweizer GmbH documentation and prepare a commercial quotation with international logistics.

Eska and model names are trademarks of their respective owners and are used only to identify the equipment for which we source parts. SpareX is not an official dealer, distributor or representative of Eska and is not affiliated with the trademark owner. Origin, documents and warranty are stated for each item in the quotation.