What is composite thermistor, overcurrent | overvoltage protector?
Composite thermistor is a combination of thermal coupling, The VDR varistor and PTC thermistor close to and packaged into one. Its main application in power meters and other power supply in the switching power supply and transformer primary At the same time to achieve the current, voltage integrated protection. Which solves the difficulty of using a single PTC thermistor in matching with the transformer. Over-voltage over-current state of the PTC thermistor protection instrument can not work properly, And cryogenic instrumentation exception PTC may not be protected And so on.
Pin description: 1,2 feet between the thermistor;
2,3 feet between the varistor;
2 feet are pressure sensitive, heat sensitive common.
Connection: 1 foot input; 2 feet output; 3 feet connected to the zero line.
When the varistor absorbs the energy when there is a large temperature rise,Due to thermal coupling, PTC thermistor temperature will rise, Plus it itself will be due to the increase in current and heat, When the temperature reaches the PTC thermistor switch temperature, Its resistance jumped,
Current drastically reduced, While its voltage drop on the increase a lot, Varistor voltage drop across the two, Only a small leakage current passes.So that the voltage of the protected circuit is reduced to the normal operating voltage range, The power meter is working properly.
Pin description: 1,2 feet between the thermistor;2,3 feet between the varistor;
2 feet are pressure sensitive, heat sensitive common.
Connection: 1 foot input; 2 feet output; 3 feet connected to the zero line.
Current drastically reduced, While its voltage drop on the increase a lot, Varistor voltage drop across the two, Only a small leakage current passes.So that the voltage of the protected circuit is reduced to the normal operating voltage range, The power meter is working properly.
| Composite thermistor commonly used models |
Curie temperature |
action Current （25℃） |
Not action Current （60℃） |
Pressure sensitive Voltage （25℃） |
Rated Maximum work Voltage |
Dimensions | |
| Tc（℃） | It(mA) | Ih(mA) | V(V) | Vmax(V) | Dmax | Hmax | |
| SPMZ11-08E300-600R/14D121 | 115±7 | 200 | 60 | 120 | 65 | 16 | 10 |
| SPMZ11-08E400-800R/14D181 | 115±7 | 200 | 50 | 180 | 120 | 16 | 10 |
| SPMZ11-10E300-500R/14D181 | 115±7 | 250 | 70 | 180 | 120 | 16 | 10 |
| SPMZ11-06E201-401R/10D391 | 85±7 | 80 | 20 | 390 | 265 | 12 | 10 |
| SPMZ11-06E151-251R/10D391 | 115±7 | 100 | 25 | 390 | 265 | 12 | 10 |
| SPMZ11-08E600-121R/12D391 | 115±7 | 180 | 40 | 390 | 265 | 14 | 10 |
| SPMZ11-10E300-500R/14D391 | 115±7 | 250 | 90 | 390 | 265 | 16 | 10 |
| SPMZ11-10E400-800R/14D491 | 115±7 | 220 | 70 | 390 | 330 | 16 | 10 |
| SPMZ11-16E200-300R/20D391 | 115±7 | 450 | 130 | 390 | 265 | 22 | 12 |
