TDK Introduces Compact ThermoFuse Varistors for Surge Protection of up to 50 kA
TDK Corporation has introduced the MT40 series of ThermoFuse varistors (ordering code B72240M), a new generation of surge protection components (SPC) that combine a compact design with advanced safety features. Thanks to their patented overmolding technology and integrated thermal disconnecting system, these SPCs provide robust protection up to 50 kA while minimizing size (38.0 x 15.2 x 40.9 mm; L x W x H). Consequently, the MT40 series is commonly used in inverters, industrial power supplies, outdoor lighting, telecommunications systems, and surge protection devices (SPDs).
Designed for extreme electrical conditions, the MT40 series has a peak surge current capability of up to 50 kA (8/20 μs pulse) and a short-circuit current rating of up to 200 kA. The series is recognized as a UL 1449 Type 1CA component assembly, designed for use in applications with AC voltages ranging from 150 V to 550 V and DC voltages spanning from 200 V to 750 V. Additional features, such as a galvanically insulated normally open micro-switch for remote monitoring and an optional visual indicator, enhance system integration and operational safety. These MT40 components operate in temperatures ranging from -40 °C to +85 °C.
Supporting sustainable design practices and aligning with TDK’s commitment to environmental responsibility, the MT40 series is encapsulated in a flame-retardant epoxy coating. Its RoHS compliance and lead-free materials underscore its eco-conscious profile while ensuring high reliability under demanding conditions. By combining innovation, safety, and sustainability, MT40 ThermoFuse varistors offer system designers a compact, future-proof solution for next-generation industrial and communication systems.
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Main applications
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PV systems
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Industrial power supplies
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Outdoor lighting systems
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Telecommunication systems
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Surge protective device (SPD)
Main features and benefits
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Strap-terminated varistor with a thermal disconnecting system
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Compact size
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Flame-retardant epoxy encapsulation
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Short circuit current rating (SCCR) up to 200 kA acc. to UL 1449
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High peak surge current up to 50 kA
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UL 1449-recognized as a type 1CA for both AC and DC applications (file number E321126)
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Normally open micro-switch for remote indication/monitoring circuit
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Same electrode footprint of PCB for all types
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RoHS, REACH, and PFAS compliant
Further information on the products can be found here.
