Railway Signal Engineering Management Railway Signal Engineering Project Management
Wiring practices and standards
Important information for Railway Signaling
;Strands,dia mm,Loop R/km,Area,Drop/ 100m/Amp (V),Dist in m (as above),Current (A) (Normal),Current (A)(Maxm),Drop in V (normal),Drop in V (Maximum),Source Voltage (V), Voltage at Load point (normal),Voltage at Load point (Maximum),Drop (Normal)%,Drop maximum)%
;Strands,Wires dia mm,Area sq mm,Current Amp
;AWG gauge,Conductor Diameter Inches,Conductor Diameter mm,Ohms per 1000 ft.,Ohms per km,Maximum amps for chassis wiring,Maximum amps for power transmission,Maximum frequency for 100% skin depth for solid conductor copper
;16,0.0508,1.29032,4.016,13.17248,22,3.7,11 k Hz
;17,0.0453,1.15062,5.064,16.60992,19,2.9,13 k Hz
;Metric 2.0,0.00787,0.2,169.39,555.61,0.51,0.088,440 kHz
;Metric 1.8,0.00709,0.18,207.5,680.55,0.43,0.072,540 kHz
;Metric 1.6,0.0063,0.16002,260.9,855.752,0.33,0.056,690 kHz
;Metric 1.4,0.00551,0.14,339,1114,0.26,0.043,900 kHz
;Metric 1.25,0.00492,0.125,428.2,1404,0.2,0.034,1150 kHz
;Metric 1.12,0.00441,0.112,533.8,1750,0.163,0.0277,1400 kHz
;Metric 1,0.00394,0.1,670.2,2198,0.126,0.0225,1750 kHz
The table below shows the distance to which one can extend a feed using various copper conductor sizes in a cable. The voltage drop follows Ohm's law and depends on the electrical resistance per unit lenth of the conductor. This is generally important in Railway Signalling in determining maximum distances high current consuming functions as point machines or signals can be driven from the nearest control location. This table indicates the maximum distance limited by voltage drop. However there can be other limitations on account of immunization imposed which is not covered here. The limitation imposed by the maximum current a particular wire size do not play important role in this as the voltage drop predominates. The tool also provides option of finding distance for conductor size of user's choice. Input the voltage and current values suiting the need in the cyan highlighted boxes and the table will get updated as the input values change. The distance is calculated such that the total drop is 10% when nominal current flows through the function.
When current flows in a wire its temperature increases due to the resistance in the wire. The temperature increase affects the material of the insulation used on the wire. The effect on the insulator also depends on factors as if it is enclosed and if there are more conductors near it. The table is based on copper cable insulated in PVC and is laid on its own. This table is useful for determining correct size of wires in internal wiring of signalling installation. It is also important in determining the protective device size like a MCB or fuse where the circuit will have to be disconnected before the maximum current rating is exceeded in the conductor. This table uses approximately 13A per square mm of the wires to arrive at the capacities. An option to check current capacities of a different configuration is included. To use this input the number of strands and the diameter of the wire in the cyan boxes and click the update boxes which will add the new size to the rows on top of the table highlighted in cyan.
Wires are manufactured to standard sizes and this table is the standard wire sized used by American wire manufacturers and so is referred as AWG meaning American wire guage.