In this section:
For information about the Power Distribution Unit (PDU), refer to Power Management.
When installing or replacing a TPA or GMA fuse, make sure that the replacement fuse is the correct fuse type and current rating. Use of an incorrect fuse may cause damage to the protected equipment, or the PDU.
The following fuse types are included with your system:
Each TPA fuse location in the PDU has an individual fuse alarm LED (red) that is lit if there is a problem with the respective load (or the fuse itself). However, the GMT fuses have only one fuse alarm LED (red) that is lit. You can identify which of the GMT fuses need to be replaced by examining each GMT fuse. The indicator on the failed fuse springs forward and should be visible on the bottom side of the fuse.
The following figure is an illustration of a typical GMT fuse.
GMT Fuse
The TPA module comprises a fuse and holder and is intended to create a power disconnect condition to the equipment to which it is connected downstream. This module creates the power disconnect by burning out in the event of an over-current condition in the downstream equipment. The fuse is only to be replaced with the power to the unit turned off and the fault condition cleared and it is not to be used as the on and off switch for the equipment to which it is connected downstream. Reconnecting a TPA module with the PDU under power with an enabled load may damage the TPA module. It is recommended that the load devices (power supplies) are switched off (or removed) before replacing a TPA fuse.
The following figure shows the mapping of TPA fuses to the DSC Platform power modules in each shelf. For information about removing a power module, refer to Replace a Faulty Power Module (PM) .
Each fuse in the PDU controls the power connection to PM1 - PM4 in each shelf.
Mapping of TPA Fuses to Power Modules
The following figure shows the power module locations.
Power Module Locations
Before replacing any fuse, be sure to clear the fault condition that caused the fuse to fail.
Start
Obtain the fuse of the recommended size.
The current rating of the fuse (in Amps) is indicated on the fuse.
Insert the new fuse into the fuse holder, as shown in the following figure.
Fuse Holder
Insert the fuse holder with the new TPA fuse into the PDU.
Press firmly on the fuse holder to make sure that it is properly seated.
Verify that the fuse alarm LED on the front of the fuse holder is off.
Reinsert the power supply in the shelf and use a multimeter, as required, to verify that the output voltage of the equipment is a nominal -48 VDC and the polarity of the negative and positive wires is correct.
Start
Obtain the fuse of the recommended size.
The current rating of the fuse (in Amps) is indicated on the fuse. The color of the indicator also corresponds to the fuse size. Use the color code chart provided with the fuse to confirm that you are using the appropriate fuse.
Using a fuse puller as shown in the following figure, remove the faulty fuse from the PDU.
It is recommended that you use a fuse puller to extract a GMT fuse: otherwise, you may break the fuse in its slot.
Fuse Puller
Insert the new fuse into the appropriate fuse slot.
The fuse alarm indicator on the PDU faceplate should be off.