Introduction
61223445L2-5B
3
Ground Fault or Short Detection
If a short or ground fault is detected, the 239 H4R will keep the relays open and continue to
monitor the customer-side interface until the fault condition clears. During the fault
condition, the network-side of that repeater can function normally, allowing for synchroni-
zation and loopback/sectionalization testing up to that repeater.
While the short or ground fault condition is present on the customer side of the repeater, the
239 H4R places a nominal –37 VDC on the customer-side, and every three seconds, will
actively monitor the customer-side for the fault to clear. Once the 239 H4R detects that the
condition is clear, the relays close, allowing span powering to pass to the customer side.
NOTE
The isolation process is only possible if the apparatus case is
properly grounded.
Electrical Characteristics
That following table lists the electrical characteristics of all four input ports of the 239 H4R in
an unpowered state.
Table 1. 239 H4R Electrical Characteristics
Subscriber Loop Test Set
Ohmmeter
T/R
T-GND
R-GND
T/R
T-GND
R-GND
NET 1
5
365K
365K
NET 1
5.8
14.4M
15.6M
NET 2
5
218K
217K
NET 2
5.8
16.1M
16.5M
CUST 1
7
91.9K
91.9K
CUST 1
5.7
24.4M
24.3M
CUST 2
6
61.2K
61.1K
CUST 2
5.9
24.0M
23.8M