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Product name: Transformer current&voltage overload protection PTC thermistor

Item: MZ31 series

Transformer current&voltage overload protection PTC thermistor

Brief Introduction:
MZ 31 series of PTC thermistor is a million- time safety device of automatic protection,recoverability, using repeatedly, and no trigger, noise or protective components that could protect and restore from abnormal temperature and current automatically,which called "auto restore fuse" and "ten-thousand-time fuse".Recoverability, using repeatedly, and no trigger, noise or sparks.  It can replace traditional fuse and widely applied in overcurrent and overload protection of motor, transformer, electronic circuit. PTC thermistor decreases its residual current through sharp resistance increasing, restraining consumption of the whole line,and it can restore its protective function after the trouble was removed.But traditional fuse could not restore after fusing in the circuit.

Primary overcurrent, overload and overvoltage protection of transformers, adapters

Working principle:
As indicated in Fig as below,when circuit is in the normal state, the current through PTC is lower than the rated current and PTC is in the normal state with small resistance value,which will not affect the normal operation of the protected circuit such as primary and secondary loops of the voltage transformer.In case of some trouble in the circuit and the current is bigger than the rated current,the PTC will become hot quicklyand present high resistance value, which sets the circuit relatively “off” to protect the circuit from damage.After the trouble is removed,PTC will automatically restore its low resistance state and the circuit will resume normal operation.

1.Automatic protection,can resume steadily after protection
2.Contactless,noiseless and flameless;
3.Has complete specification
4.Reacts fast
5.Long stability
6.With a better performance of withstanding voltage,
   suitable for operating in 250/265V AC (high resistance state) continuously
7.small steady resistance;
8.low rated current.

Choose guidelines:
In selecting PTC thermistor as overload protection component,firstly,make sure of the maximum operating current in the circuit(non-trip current of PTC thermistor) and maximum operating voltage,rated zero power resistance,and also the outlook and dimension should be also taken into consideration.Relation between operating temperature,operating current and non-operating current is as shown in Fig 3 as below.Operating current is normally 2-3 times compared as non-operating current,and both of the currents will be reduced as operating temperature increases.

Marking of Part Number:

1.Series: thermistors for overcurrent and overload protection
2.Type:1-disc,2-encased,3-pin form-coating,4-pin form non-coating,5-SMD
3.Type:A-general, B-compount, C-moduie
4.Chip size: 8-Φ8mm          9-Φ9mm         11-Φ11mm    
5.Curie temperature: F-50℃       H-75℃       N-100℃   P-120℃     K-125℃
6.R25 resistance: 6R0-6Ω     6R5-6.5Ω      70R-70Ω      121-120Ω
7.Resistance tolerance: K+/-10%        M+/-20%         H+/-25%         N+/-30%
8.Greatly voltage:250-250V         265-265V
9.Wire shape: S-Straight, A-Axis formed, U-In-formed

Dimension(Unit: mm):

Remarks:Except for the reference size and parameter above,different electrical parameter and encapsulation mode can be custom made per client's requirement.
You can send us required specifications to info@dxmht.com or provide reference samples to our factory office:
And then samples&orders can be custom made per your requirement.