COE Installation Quality Bulletin

Installation Quality Bulletin Number: 04-04

To: All Installation Suppliers / Central Office Operations Representatives / Design Engineering Representatives / Quality Managers / Field Engineering Representatives / AMC Representatives

Date: Friday, February 27, 2004

From: QWEST Installation Quality Assurance

Subject: -48VDC fuse panel assemblies equipped with KLM-type fuse positions and the observance of voltage “bleed.”

Action Required:

YES: / Ö / NO:


Description of Bulletin:
The purpose of this Quality Bulletin is to provide all Qwest-approved installation Service Suppliers and interested parties with an explanation of the presence of -48VDC voltage “bleed” on the distribution terminals of certain ADC fuse panels equipped with KLM-type fuse positions.

In past installations (with approved fuse panel assemblies from different equipment vendors), the Service supplier had been instructed to test for the existence of foreign battery when equipping a fuse position to serve new equipment. If the Service Supplier’s test indicated the presence of foreign battery, the installer would cease the installation activity and troubleshoot the source of the errant potential and remove it.

With the introduction and approval of the newest vintage of ADC fuse panel assemblies (e.g., PWX-J41RCK4XXYSPWP and the PWX- J41RCK4G1YSPWP - refer to SK-A and SK-B), there has been a change to this policy. Because of the design of these panels, the Service Supplier will observe what appears to be a foreign -48VDC potential on these terminals once the entire panel has been energized (even if each individual fuse position is unequipped with a corresponding KLM-type fuse).

This is a normal condition for this fuse panel assembly. The reason that this voltage “bleed” exists has to do with the design of the electronic fuse alarm circuit. The voltage that is being read across the distribution terminals is bleeding off of the printed circuit board of the alarm system.

This condition does not exist with other manufacturer’s fuse panel assemblies primarily because those panels employ a mechanical alarm system which negates the bleed voltage. For the other ADC fuse panel assemblies that also contain GMT-type and TPA-type fuse positions, there is no voltage bleed on those terminal types. The voltage “bleed” effect is isolated only to those fuse panels that contain the KLM-type fuse positions. Refer to Table A for the various types of approved AMC configurations that utilize these KLM-type fuses.

Note: ADC maintains that although there is an observable and measurable voltage present on these terminals, the subsequent current associated with it is negligible and poses no physical threat or danger to the Service Supplier. The measurable current associated with this voltage is 0.0005A (0.5mA). The Service Supplier is encouraged to verify this reading with a multimeter (set to an amperage range of 10mA across the -48V & RTN terminals).

Acknowledgements to Bob Kjera (Qwest AMC) and Daniele Nepper and Cindy Olson (ADC) for their contributions to the content of this Bulletin.

Qwest Installation Quality Assurance
Jeff Bostow
612-798-2460

mailto:

SK-A

PARTIAL REAR VIEW OF PWX-J41RCK4XXYSPWP

SK-B

PARTIAL REAR VIEW OF PWX-J41RCK4G1YSPWP

TABLE A

PART NO. / AMC CONFIGURATION ID. / GMT / KLM
PWX-J41RCK4XXYSPWP / C-CMNSYS-DCPFPNL-2LD-4KLM / 4+4 / -
PWX-J41RCK5XXYSPWP / C-CMNSYS-DCPFPNL-2LD-5KLM / 5+5 / -
PWX-J41RCK2G4YSPWP / C-CMNSYS-DCPFPNL-2LD-2KLM+4GMT / 4+4 / 2+2
PWX-J41RCK2G1YSPWP / C-CMNSYS-DCPFPNL-2LD-2KLM+10GMT / 10+10 / 2+2
PWX-J41RCK4G4YSPWP / C-CMNSYS-DCPFPNL-2LD-4KLM+4GMT / 4+4 / 4+4
PWX-J41RCK4G1YSPWP / C-CMNSYS-DCPFPNL-2LD-4KLM+10GMT / 10+10 / 4+4
PWX-J41FCK4G4YSPWP / C-CMNSYS-DCPFPNL-2LD-4KLM+4GMTFA / 4+4 / 4+4
PWX-U41R3K6G2YSPWP / C-CMNSYS-DCPFPNL-6LD-2KL+2LD-2GM / (2) 2 / (6) 2