TOA Electronics FPS1000-48, FPS-S1U Connecting the Load, Load Wiring, Current Carrying Capacity

3.7 CONNECTING THE LOAD

WARNING

Turn off the AC input power before making or changing any rear panel connection. Ensure that all connections are securely tightened before applying power. There is a potential shock hazard when using a power supply with a rated output greater than 40V.

3.7.1 Load Wiring.

The following considerations should be made to select wiring for connecting the load to the power supply: * Current carrying capacity of the wire (refer to 3.7.2).

*Insulation rating of the wire should be at least equivalent to the maximum output voltage of the power supply.

*Maximum wire length and voltage drop (refer to 3.7.2).

*Noise and impedance effects of the load wiring (refer to 3.7.3).

3.7.2 Current Carrying Capacity

Two factors should must be considered while selecting the wire size. 1.Wires should be at least heavy enough not to overheating while carrying the power supply load current at the rated load, or the current that would flow in the event the load wires were shorted, whichever is greater.

2.Wire size should be selected to enable voltage drop per lead to be less than 1.0V at the rated current. Please refer to Tables 3-2 and 3-3 for maximum wire length to limit the voltage drop in American and European dimensions respectively.

wire size	Resistivity	Maximum length in Feet to limit voltage
AWG	Ohm/kft	drop to 1V or less.
		5A	10A	20A	50A	150A
14	2.526	80	40	20	8	2
12	1.589	120	60	30	12	3.4
10	0.9994	200	100	50	20	6
8	0.6285	320	160	80	32	10
6	0.3953	500	250	125	50	16
4	0.2486	800	400	200	80	26
2	0.1564	1200	600	300	125	40
0	0.0983	2000	1000	500	200	68

Table 3-2:Maximum wire length for 1V drop on lead (in feet).

Cross sect.	Resistivity	Maximum length in meters to limit voltage
Area	Ohm/km	drop to 1V or less.
(mm^2)		5A	10A	20A	50A	150A
2.5	8.21	24.0	12.0	6.0	2.4	0.8
4	5.09	39.2	18.6	9.8	4.0	1.4
6	3.39	59.0	29.4	14.8	5.8	2.0
10	1.95	102.6	51.2	25.6	10.2	3.4
16	1.24	160.0	80.0	40.0	16.0	5.4
25	0.795	250.0	125.0	62.0	25.2	8.4
35	0.565	354.0	177.0	88.0	35.4	11.8

Table 3-3:Maximum wire length for 1V drop on lead (in meters).

For currents not shown in Tables 3-2 and 3-3 , use the formula : Maximum length=1000/(current*resistivity)

Where current is expressed in ampers and resistivity in ohms/km or ohms/1000ft.

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