APPENDIX B: DC Power Input. Black Box LBH184A, LBH181A, LBH081A, LBH082A, LBH084A, LBH182A

Appendix B

APPENDIX B: DC Power Input

B1.0 Specifications for LBH08x/LBH18x Switches, DC Power at 12, 24 and

–48VDC Power input

Each Black Box LBH08x/LBH18x Switch requires DC power input, at 12, 24 and 48VDC. The wide range of DC power input types qualifies this product for use in

12, 24 and 48 applications in different industries.

DC Power Terminals: “+”, “

-

” are internally floating so that user may ground either

GND: ground wire connection to the chassis (#6-32 thread)

Power Consumption:

8 watts typical, 9 watts Max.

12VDC Power Input nominal (range 9 to 15VDC)

B2.0 12, 24 and –48VDC

POWER, THEORY OF

OPERATION

24VDC Power Input nominal (range 18 to 36VDC)

-48VDC Power Input nominal (range 36 to 60VDC)

The 12, 24 and -

48VDC power options are designed using diodes inside on each DC power input line behind the two external power connection terminals, so that the power from an external source can only flow into the hub. This allows the Switch to operate only whenever DC power is correctly applied to the two inputs. It protects the Switch from incorrect DC input connections. An incorrect polarity connection, for example, will neither affect the Switch, its internal power supply, nor will it blow the fuse in the internal power supply.

B3.0 APPLICATIONS FOR DC POWERED ETHERNET SWITCHES

Black Box LBH08x/LBH18x Switches are easily installed in a variety of applications where 12, 24 and -48VDC power is used as the primary power source.

The DC power configuration capability provides an Ethernet networking solution utilizing a special power supply in switches with a proven track record.

The –48VDC solution is particularly useful in the telecommunication industry, where it is common for facilities to operate on -48VDC power. Such companies include regular and wireless telephone service providers, Internet Service

Providers (ISPs) and other communication companies. In addition, many high availability equipment services, such as broadcasters, publishers, newspaper operations, brokerage firms and other facilities often use a battery backup system to maintain operations in the event of a power failure. It is also frequently used for computer system backup, management and operations monitoring equipment.

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Appendix B

The 24VDC option is particularly useful in the industrial environment, where it is common for facilities to operate on 24VDC power. The 24VDC applications are mainly in heavy duty industrial automation such as factory floor, process plants,

HVAC, military equipment, etc.

B4.0 12, 24 and –48VDC INSTALLATION

This section describes the proper connection of the 12, 24, –48, leads to the

DC power terminal block on the LBH08x/LBH18x Switch. The DC terminal block on the LBH18x Switch is located on the right side of the unit and the LBH08x terminal block is located on the left front and both are equipped with four (4) screw-down lead posts. The power terminals are identified as positive (+) and negative (-), and they are electrically floating inside the unit so that either may be grounded by the user if desired. The chassis is “earth” or ground (GND).

The connection procedure is straightforward. Simply insert the DC leads to the Switch’s power terminals, positive (+) and negative (-) screws. The use of Ground

(GND) connects to the Switch chassis screw provided under the DC terminal. Ensure that each lead is securely tightened.

Fig B4.0a LBH18x Power Input

Fig B4.0b LBH08x Power Input

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Appendix B

NOTE: Always use a voltmeter to measure the voltage of the incoming power supply and figure out the +ve potential lead or -ve potential lead. The more +ve potential lead will connect to the post labeled “+ve” and the rest to the “-ve”. The GND can be hooked up at the last.

When power is applied, the green PWR LED will illuminate.

Note: The GND should be hooked up first. The switch has a floating ground, so the user may elect to Ground either + or - terminal to suit the customer’s use.

Before connecting live power lines to the Terminal Block of –48VDC,

12VDC and 24VDC always use a digital voltmeter to measure the output voltage of the power supply and determine the lead which is more “+ve potential”. The more “+ve” voltage lead from 48V or –48V supply must be connected to the post labeled “+”.

B4.1 UL Requirements for DC-powered units

CAUTION: 48VDC products shall be installed with a readily accessible disconnect device in the building installation supply circuit to the product.

Minimum 18AWG cable for connection to a Centralized DC power source.

1. Minimum 14AWG cable for connection to an earth wiring.

2. Use only with Listed 10A circuit breaker provided in building installation.

3. “Complies with FDA radiation performance standards, 21 CFR subchapter

J.” or equivalent.

4. Fastening torque of the lugs on the terminal block: 9 inch-pound max.

5. To secure a centralized DC Power Source cable , use at least four cable ties to secure the cable to the rack at least 4 inches apart, with the first one

located within 6 inches of the terminal block.

B5.0 TROUBLESHOOTING

Please refer to Section 5.0 for troubleshooting.

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LBH081A, rev. 1

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