Nortel Networks DCT1900 manual ⎛ U

Technical Product Manual - DCT1900

Configuration Directions, Base Station Powering

		n	⎛		U		2		4⋅ R	⎞
l	=		⋅⎜					−		⎟
						⋅ R			R
max	4		⎜ P							⎟
			⎝	Base			tp		tp	⎠

where:

n = number of twisted pairs (when using data pairs only: n=2) U = power supply voltage

PBase = worst case power consumption of Base Station = 7.5W

Rtp = resistance of twisted pair per meter (double value of single wire) R = dc losses in filters, transformers and connectors = 1

If the supply voltage is 42 Volts or lower, the following formula must be used to calculate to the power limited lengths:

	⎛U		⋅(U −U		)		R ⎞
l	= n⋅⎜	min		min		−		⎟
		P		⋅R
max	⎜						R ⎟
	⎝		Base	tp			tp ⎠

where:

n = number of twisted pairs (when using data pairs only: n=2) U = power supply voltage

Umin = minimum input voltage of Base Station = 21V

PBase = worst case power consumption of Base Station = 7.5W

Rtp = resistance of twisted pair per meter (double value of single wire) R = dc losses in filters, transformers and connectors = 1

Tables 4-3 and 4-4 give the power consumed by the Base Stations and their cables for different supply voltages. The consumed power ranges from about 7.5W for zero length cables to 15W maximum cable lengths (given in Table 4–2). The consumed power has been calculated using the following formula:

	2		⎛l´Rtp			⎞
			⎜			⎟
	U − U −4⋅⎜			n		+R⎟⋅PBase
P=U⋅			⎝			⎠
		⎛l⋅R				⎞
		⎜		tp		⎟
	2⋅⎜		n		+R⎟
		⎝				⎠

where:

n = number of twisted pairs (when using data pairs only: n=2) U = power supply voltage

PBase = worst case power consumption of Base Station = 7.5W

Rtp = resistance of twisted pair per meter (double value of single wire)

R = dc losses in filters, transformers and connectors = 1 l = length of the cable

4-4	Config-DCT1900/R8/mw
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