Machine Design

Overheating Protectors

Three models of thermal protectors protect against overheating in ac and dc equipment.

The JP7, EP2, and BP protectors feature automatic reset and sharp "snap-action" sound upon activation. A dual-spring mechanism protects against shock and vibration by creating more tension on the contact.

Model JP7 measures 17.0 X 7.3 X 3.9 mm and is for ac equipment in harsh environments. Performance qualities include a 75 to 150°C operating range with tolerances of ±5, ±7, and ±10°C. Contact ratings are 8 A/125 Vac resistive and 5 A/250 Vac ac to 10,000 cycles. Applications include motors, transformers, solenoids, lighting fixtures, heating pads, heaters, and resistors for motor control.

The similar EP2 has casing material designed specifically for low-voltage dc equipment such as accessory motors, inverter systems, PC boards, and switching power supplies. Temperature setpoint range is 75 to 130°C with tolerances of ±5, ±7, and ±10°C. Contact ratings are 26 V/13 A dc resistive to 10,000 cycles.

The BP protector is designed to automatically shut off rechargeable battery packs. It comes in Ni-Cd, Li-ion, Ni-MH versions. The 15 5 2.8-mm device has an operating range of 70 to 100°C with tolerances of ±5, ±8, and ±10°C. Contact ratings are 18 V/ 5 A dc resistive and 15 V/15A dc resistive to 6,000 cycles. Various nickel strip, wire termination, and insulating sleeve options are available.

Selco/ECC, 605 S. East St., Anaheim, CA 92805, (800) 229-2332,

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