Applications: It is used for railway communication, fire alarming signal, telegraph, automatic signal device, and other equipments within audio frequency range of A.C. 500V or lower.     
Working Conditions: 
1.The cable is used under ambient temperature of -40~+50℃, it may be installed on the line with any level difference;
2. Allowed conductor temperature ofr long-term working is +70℃;
3. The cable of common structure is suitable for the equipment under working frequency of D.C. equipments;
4. The cable with complex stranded core is suitable for the equipments within audio frequency range and electric division with need of shielded cable;
5. The common cable may be laid under environment temperature of no lower than 0℃;
6. The cable with coldness-proof sheath may be laid under environment temperature no lower than -10℃;
7. Cable bending radius for installation should be no less than 15 times that of cable outer diameter.  



2. The insulation resistance between cable cores or between core and steel tape should be no less than 25MW under condition that cable length is 1km and environment temperature is 20℃. 
3.The cable could endure voltage test of 1500V for 5 minutes without puncture.