ADC H2TU-C-231 POWER CONSUMPTION, MAXIMUM POWER DISSIPATION, MAXIMUM CURRENT DRAIN

LTPH-UM-1109-01, Issue 1 Appendix A - Specifications

POWER CONSUMPTION

The three most important power parameters of an H2TU-C are its maximum power consumption, maximum power dissipation, and maximum current drain.

Table 20 describes line-powered and locally powered circuits on 9 kft, 26 AWG loops.

Table 20. H2TU-C-231 Power Parameters

	-48 Vdc Power	Heat Dissipation	-42.5 Vdc Current
	Consumption
		(Watts)	(mA)
	(Watts)
Remote Power Source	Maximum	Maximum	Maximum
Line-powered	12.0	7.0	286.0
Locally powered	8.6	6.7	205.0

MAXIMUM POWER DISSIPATION

The maximum power dissipation measures the power that is converted into heat that builds up within the unit. It contributes to the total heat generated in the space around the unit. It is used to determine the maximum number of fully loaded shelves per bay that does not exceed the maximum allowable power dissipation density in watts per square foot to comply with GR-63.

In COs, the maximum power dissipation for open-faced, natural convection-cooled mountings is limited to

134.7watts per square foot per GR-63-CORE. The footprint of a standard 28-slot, 23-inch HCS-417 shelf is

7.024 square feet. Therefore, the maximum bay dissipation is limited to 946 watts. Use this limit and the parameters in Table 20 to determine the maximum number of H2TU-C circuits that can occupy one CO bay.

This is a worst case situation since it assumes the entire CO is subjected to the maximum power density. More favorable conditions would permit increasing the number of shelves per bay without jeopardizing the CO thermal integrity.

The thermal loading limitations imposed when using the H2TU-C in a Controlled Environmental Vault (CEV) or in other enclosures are determined by applying its power parameters to the manufacturer's requirements for each specific housing.

The -48 Vdc power consumption is the maximum total power that the H2TU-C-231 consumes or draws from the shelf power source. This parameter is needed when the H2TU-C-231 is in a location remote to the CO it is serving. It determines the battery capacity required to maintain an 8-hour standby battery reserve for emergency situations. Battery capacity, therefore, limits the maximum number of line units that can be installed in a remote enclosure. Use the data in Table 20 to perform this analysis.

MAXIMUM CURRENT DRAIN

The maximum current drain is the maximum current drawn from the shelf power supply when it is at its minimum voltage (-42.5 Vdc). This determines the shelf fusing requirements. Use the -42.5 Vdc current data in Table 20 to determine the shelf fusing requirements for your particular H2TU-C applications.

H2TU-C-231 List 2 January 9, 2002 55