Sage 930i, Operating Manual

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5-29 © Sage Instruments 2000
9100-2930-02 01/31/00
Sage Instruments 930i Communications Test Set
5-7.1 Loop Supervision Thresholds Other Than 48 V DC
To set the loop line signalling threshold:
1. Set the 930i to
NORMAL LOOP CONTACT 2W 600
or
900
under the Trunk Type function key.
(Refer to Section 3-2.1, Trunk Type Function Key, for setup information.)
2. Press the Up/Down Arrow keys to scroll through the option menus, or select 7 using the
numeric keypad and then press the Option Menu key. The display reads:
OPTION MENU #: 7 SUPERVISION THRESHOLDS
K1 K2 K3 K4
3. Press ENT or any soft key (K1-K4) to activate your selection. The display reads:
NO INDICATION IF LOOP <3 V DEFAULT
K1 K2 K3 K4
The display above shows that if there is no talk battery present (“dry” loop), there will be no voltage
across the loop, and the 930i will turn off all line signalling LEDs. This threshold is preset at 3 V. For this
example, this value will be adequate.
4. Press K1, K2, or K3 to advance the display to the next choice. The display reads:
ORIG OFF HOOK IF LOOP < 39 V DEFAULT
K1 K2 K3 K4
When the originate, or CONTACT, side of the circuit goes off-hook, it closes the loop between Tip and
Ring (2-wire) or TR and T1R1 (4-wire). This lowers the voltage difference across the loop. On a short
loop, or near the contact end of the circuit, this voltage will be very small. Near the battery (Central Office)
end on a long loop, this voltage can remain fairly large. The 930i sees the CONTACT end as being off-
hook when the voltage across the loop falls below 39 V. If a PBX is being tested and it is powered from
-24 V instead of -48 V, the threshold of the 930i should be set to about 20 V.
To set the threshold to 20 volts:
1. Use the numeric keypad to enter the number 20.
2. Press the ENT key. This value will now be remembered by the 930i.
3. Press K4 under
DEFAULT
when you have finished testing or the readings will be incorrect when
you return to normal 48 V trunks. The default value is 39 V.
Option Menu #:
7
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