Application examples
Protection of motors, batteries, transformers, chargers, power supplies, LED lighting and PCBs; heating-pad temperature control.
KUNANTENSEIBETTERFUSE / KSD05 SERIES
KSD05 Thermal Protector
Bimetal thermal protection
with automatic reset after cooling.
BETTERFUSE / KSD05AUTO-RESET PROTECTOR
Product image from manufacturer catalog60–150°C
5AAC 250 V
±5°COperating tolerance
NC / NOContact options
03AUTO-RESET THERMAL PROTECTION
Sense temperature.
Switch contact state.
A compact bimetal thermal protector with a PBT plastic or metal case and an epoxy seal. Check lead, terminal and case options against your mounting requirements.
The manufacturer highlights compact size, quick action and responsive thermal behavior. AC and DC ratings are specified as distinct voltage/current combinations.
NC contacts open on temperature rise and close again after cooling; NO contacts behave in the opposite way. Account for the equipment’s restart behavior when the protector resets automatically.
—TECHNICAL DATA
Specifications
- Electrical ratings
- AC 250 V / 5 A
AC 115 V / 8 A
DC 24 V / 10 A - Contact resistance
- ≤50 mΩ
- Operating temperature
- 60–150°C / ±5°C
- Temperature options
- 5°C steps
- Reset behavior
- Automatic reset
- Case & seal
- PBT plastic / metal; epoxy seal
Contacts & case options
NC
All listed temperatures: plastic or metal case
NO
60–125°C: plastic case only. The source does not list NO options at 130–150°C or NO metal-case versions.
Use the rating specified for the actual supply and load; do not transfer current ratings between voltages.
| Operating temp. (°C) | Reset temp. (°C) | Maximum ambient temp. (°C) | NO option |
|---|---|---|---|
| 60±5 | 45±8 | 110 | Plastic case |
| 65±5 | 48±10 | 115 | Plastic case |
| 70±5 | 50±12 | 120 | Plastic case |
| 75±5 | 53±14 | 125 | Plastic case |
| 80±5 | 55±15 | 130 | Plastic case |
| 85±5 | 60±15 | 135 | Plastic case |
| 90±5 | 65±15 | 140 | Plastic case |
| 95±5 | 70±15 | 145 | Plastic case |
| 100±5 | 70±15 | 150 | Plastic case |
| 105±5 | 75±15 | 155 | Plastic case |
| 110±5 | 75±15 | 160 | Plastic case |
| 115±5 | 80±15 | 165 | Plastic case |
| 120±5 | 85±15 | 170 | Plastic case |
| 125±5 | 85±15 | 175 | Plastic case |
| 130±5 | 90±15 | 180 | — |
| 135±5 | 95±15 | 180 | — |
| 140±5 | 100±15 | 180 | — |
| 145±5 | 100±15 | 180 | — |
| 150±5 | 105±15 | 180 | — |
Reset temperatures are reference values from the manufacturer. Maximum ambient temperature is distinct from operating temperature; confirm permitted conditions in the selected specification.
—CONSTRUCTION / mm
Check the outline against your mounting.
Wire type, color and length, sleeve specifications and length, and tinned copper lead length can be discussed with the manufacturer.
—APPLICATION / INSTALLATION
Consider the application and installation together.
Thermal contact
Install at a point sensitive to temperature rise, with the sensing surface in effective contact with the protected part or facing the protected area. Avoid pressure from sharp tools and heavy impacts.
Storage & evaluation
Store in a ventilated, clean, dry, non-corrosive environment below 90% relative humidity and at or below 40°C. Evaluate load current, temperature response and reset behavior in the actual equipment.
Source: Betterfuse OT Catalog_202502, printed pages 17–18. The catalog lists TUV, UL, CQC and RoHS information. Verify documentation and applicable conditions for the specific model. Application examples do not establish suitability for individual equipment.
—SERIES COMPARISON
Start with operating behavior.
| Parameter | BTT | KSD02 | KSD05 |
|---|---|---|---|
| Operation | Non-resetting | Automatic reset | Automatic reset |
| Rating at AC 250 V | 10 A / 15 A | 2 A | 5 A |
| Temperature options | Tf 73–257°C | 40–150°C (±5°C) | 60–150°C (±5°C) |
| Intervals | 21 discrete ratings | 5°C steps | 5°C steps |
| Contacts | Normally closed; opens once | NC / NO, temperature-dependent | NC / NO, temperature-dependent |
| Product details | BTT ↗ | KSD02 ↗ | KSD05 ↗ |
BTT Tf and KSD operating temperature are different specifications. Equal temperature values do not establish interchangeability; also check the load, reset behavior and installation.
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