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MZ11A Filament Preheating PTC Thermistor WMZ12A For Telecom Over Current Protection
I General Of The MZ11A Filament Preheating PTC Thermistor WMZ12A
WMZ12A(Ⅰ/Ⅱ)Series is the new generation of components for over current protection. Its safety characteristics passed the
testing and meet the requirements of UL1434. It can do protection and recovery automatically and repetitively without contacting
spot, noise and spark. WMZ12A(Ⅰ/Ⅱ)Series PTC Thermistor is designed specially for over current protection of the Ballast / CFL /
Adaptor / Charger / Watt-hour Meter / Multimeter / Telecom / Micromotor etc, as show as the example of application. When the
circuit protected is at normal state, current through the PTC thermistor will be lower than its Max. Non-operating Current (IN).
At this time Rt is at low-resistance state, and it won’t affect the normal work of the circuit protected. While abnormal things (such
as over current ) happen, the current will be much higher than its Trip Current (IT), and then Rt will change into high-resistance state
very quickly. So the circuit protected will be at open state and non-damaged. After the abnormal things disappear and the
temperature & the current recover to normal state, Rt will return to low-resistance state automatically and the circuit protected will
recover to normal operating state.
Rt’s current characteristics is the most important thing to be considered when make a choice of WMZ12A(Ⅰ/Ⅱ)series. Its Max.
Non-operating Current shall be reasonably higher than rated operating current through the circuit protected and the criterion is
that Rt can respond in time and won’t trip by mistake. Furthermore, another thing must be especially noticed is: Rt’s Max. Operating /
Non-operating characteristics is closely correlative with the ambient temperature. IT & IN will decrease while the ambient temperature
increases, as show as Figure II.
II Features Of The MZ11A Filament Preheating PTC Thermistor WMZ12A
• Non-contact circuit and component protection
• Automatically limit overcurrent
• Automatic recovery after troubleshooting
• No noise and no sparks when working
• Reliable and easy to use
IV Application principle Of The MZ11A Filament Preheating PTC Thermistor WMZ12A
Connect the WMZ12A PTC thermistor in series with the power circuit. When the circuit is in a normal state, the current flowing through the PTC is less than the rated current, the PTC is in a normal state, and the resistance is small, which does not affect the normal operation of the protected circuit such as the electronic ballast (energy-saving lamp, transformer, multimeter). When the circuit current greatly exceeds the rated current, the PTC suddenly heats up and the resistance suddenly increases to a high impedance state, thereby limiting or blocking the current and protecting the circuit from damage. After the current and current return to normal, the PTC also automatically returns to the low resistance state, and the circuit resumes normal operation.
WMZ12A PTC thermistor in the field of overcurrent protection applications such as electronic ballasts (energy-saving lamps, transformers, multimeters), Yaxun is the first to introduce the WMZ12 model featuring high withstand voltage (V ≥ 300V AC).
WMZ12A (I) is mainly used for overcurrent protection such as charger, adapter (primary coil), electric
energy meter, digital multimeter, etc.
| model | MAX Non OperaTIng Current at 25℃ In (mA) | Trip Current at 25℃ It (mA) | Rated zero power resistance value R 25 (Ω) | Maximum operating current I max (A) | Dimensions(mm) | |||
| Dmax | Tmax | d±0.05 | F±1 | |||||
| WMZ12A-70LB15RM080 | 80mA at 40℃±2℃ | 160 | 15±20% | 1.0 | 8 | 5 | 0.6 | 5 |
| WMZ12A-70LB12RM090 | 90mA at 40℃±2℃ | 180 | 12±20% | |||||
| WMZ12A-70LB10RM100 | 100mA at 40℃±2℃ | 200 | 10±20% | |||||
| WMZ12A-75S222RM005 | 5 | 10 | 2200±20% | 0.2 | 4 | 4.5 | 0.5 | 5 |
| WMZ12A-75S152RM006 | 6 | 12 | 1500±20% | |||||
| WMZ12A-75S102RM008 | 8 | 16 | 1000±20% | |||||
| WMZ12A-75S681RM010 | 10 | 20 | 680±20% | |||||
| WMZ12A-75S471RM012 | 12 | 24 | 470±20% | 0.3 | ||||
| WMZ12A-75S331RM015 | 15 | 30 | 330±20% | |||||
| WMZ12A-75S221RM018 | 18 | 36 | 220±20% | |||||
| WMZ12A-75S151RM020 | 20 | 40 | 150±20% | 0.4 | ||||
| WMZ12A-75S101RM025 | 25 | 50 | 100±20% | |||||
| WMZ12A-75A471RM014 | 14 | 28 | 470±20% | 0.4 | 6.5 | 4.5 | 0.6 | 5 |
| WMZ12A-75A331RM017 | 17 | 34 | 330±20% | |||||
| WMZ12A-75A221RM020 | 20 | 40 | 220±20% | 0.5 | ||||
| WMZ12A-75A151RM024 | 24 | 48 | 150±20% | |||||
| WMZ12A-75A121RM026 | 26 | 52 | 121 ±20% | |||||
| WMZ12A-75A101RM028 | 28 | 56 | 100±20% | 0.6 | ||||
| WMZ12A-75A68RM032 | 32 | 64 | 68±20% | |||||
| WMZ12A-75A47RM040 | 40 | 80 | 47±20% | |||||
| WMZ12A-75B331RM020 | 20 | 40 | 330±20% | 0.8 | 8 | 4.5 | 0.6 | 5 |
| WMZ12A-75B221RM025 | 25 | 50 | 220±20% | |||||
| WMZ12A-75B151RM030 | 30 | 60 | 150±20% | |||||
| WMZ12A-75B101RM035 | 35 | 70 | 100±20% | 1.0 | ||||
| WMZ12A-75B82RM040 | 40 | 80 | 82±20% | |||||
| WMZ12A-75LB82RM035 | 35mA at 60℃±2℃ | 90mA at 25℃±2℃ | 82±20% | 1.0 | 9 | 4.5 | 0.6 | 5 |
| WMZ12A-75LB68RM040 | 40mA at 60℃±2℃ | 100mA at 25℃±2℃ | 68±20% | 1.2 | ||||
| WMZ12A-75LB47RM045 | 45mA at 60℃±2℃ | 110mA at 25℃±2℃ | 47±20% | |||||
| WMZ12A-75LB33RM050 | 50mA at 60℃±2℃ | 125mA at 25℃±2℃ | 33±20% | |||||
The WMZ12A PTC thermistor is mainly used for overcurrent protection of [transformer (adapter) / primary coil / charger / digital multimeter / smart meter / micro motor / transistor]. Directly connected in series in the load circuit, when the line is in an abnormal situation, it can automatically limit the over current or block the current, and then return to the original state after the fault is removed, commonly known as "10,000 times fuse"