Ground Faults

150-409-115-05, Issue 5

 

 

GROUND FAULT ISOLATION

Solutions for common problems that may occur with the EDU-409 List 1 are listed in Table 7.

 

Table 7. Fault Isolation Guide

 

 

Problem

Solution

 

 

LED does

1 Verify that the ELU is installed and operational in the Central Office.

not light

2 Verify proper cabling between the doubler enclosure and the Central

 

Office.

 

3 Measure 100 to 200 Vdc between pins 5 or 6 and 8 or 9. This voltage

 

peaks every 15 to 30 seconds as the ELU cycles between self test and

 

line power. If less than 100 Vdc is present, check the cabling or the ELU.

 

Only the line units mentioned in the Description and Features section

 

can be used to power doublers. Other ELU models may not provide

 

reliable operation and should not be used.

 

 

LED

Synchronization is being attempted with the upstream unit.

continues to

 

flash green

 

once a

 

second

 

 

 

EDU-409

The ELU at the Central Office is not present. Measure the resistance of the

List 1 loses

HDSL input loop. Resistance should be normal loop resistance plus the

power

25 Ω signature of the ELU.

 

 

HDSL line

A grounded pair is being detected by either the ELU or EDU-409 List 1 in

power only

Span 1. This causes the unit’s ground fault detection (GFD) circuit to

appears in

trigger, which forces the HDSL line voltage off immediately after it cycles

very short

on. Remove the ELU and EDU-409 List 1 and check for cable ground faults

bursts

in Span 1. The doubler’s GFD circuit can easily be checked by grounding

 

any of the loop connectors to the doubler. This forces the circuit down

 

immediately. If the circuit stays up, either the GFD circuit is defective or the

 

EDU-409 List 1 is not properly grounded.

 

 

EDU-409

A grounded pair is being detected by the EDU-409 List 1 in Span 2. Remove

List 1 shuts

EDU-409 List 1 and check for ground fault in Span 2.

off after

 

Span 1

 

comes up

 

20

January 26, 2000

EDU-409 List 1