BH Series Snap-Action Thermostat for Transformer 17AM020A3
BH Series Thermostat / Miniature Thermal Protector / Rechargeable Battery Thermostat
Operating Principle and Structure
BW & BH series thermostats provide reliable protection against over-current and over-temperature conditions. These sealed units feature small internal resistance, silent operation, and automatic reset functionality. When current passes through the temperature-sensitive bimetal element, abnormal conditions cause the bimetal to change state, either opening or closing the circuit as needed. BH series offers enhanced safety with no temperature lag during sudden high-current events.
Technical Specifications
| Parameter |
Specification |
| Electrical Rating |
DC-12V max 12A; DC-24V max 10A; AC-125V max 8A; AC-250V max 16A |
| Open Temperature |
(30~150)±5°C; 5°C increments |
| Reset Temperature |
2/3 of action temperature ±15°C (custom specifications available) |
| Life Cycle |
10,000 operations |
| Dimensions |
L15mm × W7.1mm × H3.8mm |
| Lead Wire |
#22 3266, end half tripping, 70mm length (custom lengths available) |
| UL File No. |
E487478 |
| CQC Certificate No. |
CQC16002142880 |
| TUV Certificate No. |
B160592241002 |
Model Dimensions and Variations
| Model |
Case |
Length (mm) |
Width (mm) |
Height (mm) |
Voltage & Current |
Lead Wire |
| H20 |
Plastic |
18.5 |
8 |
4 |
DC-12V max 12A; DC-24V max 10A; AC-125V max 8A; AC-250V max 10A |
#20 3135, end 5mm half tripping, 70mm length (custom available) |
| H21 |
Metal |
18.5 |
7.3 |
3.8 |
- |
- |
| H21 |
Metal |
20 |
8 |
4 |
AC250V 20A |
#16 3135 |
| BH-A1D |
Metal |
15 |
6.6 |
3.2 |
DC-12V max 12A; DC-24V max 10A; AC-125V max 8A; AC-250V |
#20 3135, #22 3266, #22 3135, end 5mm half tripping, 70mm length (custom available) |
| BH-B2D |
Plastic |
15 |
7.1 |
3.8 |
- |
- |
| BH-TB02B-B8D |
Plastic |
15 |
5.2 |
2.4 |
DC-12V max 4A; DC-24V max 3A; AC-125V max 3A; AC-250V max 2A |
3266-AWG24#, 3135-AWG24# or nickel strip, 70mm length (custom available) |
Applications and Installation
BH series thermal protectors serve as effective and reliable safety devices for various applications including:
- 1.5 horsepower motors
- Lighting devices and ballasts
- Inverter welding machines
- Switch mode power supplies
- Rechargeable battery packs
- Portable power tools
- Fluorescent lamp ballasts
- Various electrical equipment and appliances
Enforced models capable of withstanding 3.5MPa pressure are suitable for built-in installation in plastic-coated motors.
Temperature Code Reference
| Code |
Temperature |
Code |
Temperature |
| 30 |
30°C |
100 |
100°C |
| 35 |
35°C |
105 |
105°C |
| 40 |
40°C |
110 |
110°C |
| 45 |
45°C |
115 |
115°C |
| 50 |
50°C |
120 |
120°C |
| 55 |
55°C |
125 |
125°C |
| 60 |
60°C |
130 |
130°C |
| 70 |
70°C |
135 |
135°C |
| 75 |
75°C |
140 |
140°C |
| 80 |
80°C |
145 |
145°C |
| 85 |
85°C |
150 |
150°C |
| 90 |
90°C |
|
|
BW Series & H20/H21 Series Thermal Protectors
Operating Principle and Structure
H20 and H21 series universal and enhanced protectors feature large metal casings with thermal conductive properties. The design includes bimetallic components welded with silver alloy contacts, conductive brackets, insulation fixation stands, fixed contact strips, and heat-resistant cables. During abnormal operation, rising ambient temperatures trigger the bimetallic element to quickly open the contacts and disconnect the circuit. Automatic reset occurs when temperatures return to safe operating levels.
Technical Specifications
| Parameter |
Specification |
| Electrical Rating |
DC-12V max 12A; DC-24V max 10A; AC-125V max 8A; AC-250V max 16A |
| Open Temperature |
(30~150)±5°C; 5°C increments |
| Reset Temperature |
2/3 of action temperature ±15°C (custom specifications available) |
| Life Cycle |
10,000 operations |
| Contact Closure Resistance |
≤50mΩ |
| Insulation Resistance |
≥100mΩ |
| Electric Strength |
AC1500V/1min (no breakdown or flashover) |
| UL File No. |
E487478 |
| CQC Certificate No. |
CQC16002142880 |
| TUV Certificate No. |
B160592241002 |
Applications
H20 and H21 series thermal protectors are suitable for rechargeable batteries, ballasts, massagers, micro motors, transformers, electric tools, heating appliances, and various instruments.
Certifications: UL, CQC, TUV, and RoHS compliant.
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