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FSK Trip Test Facilities
7.8 General Description
The optional Trip Test is designed to test FSK
two-frequency or three-frequency transfer trip
units using the UPLC™ or TCF–10B. Two trans-
mitters with trip test, one at each end of the line,
are needed to perform this testing function.
Trip testing is not functional on 3-terminal lines.
The Web pages and Timing Diagrams for the trip
test are shown at the end of this chapter.
The Trip Test can be used to functionally test the
transmitters and receivers at both ends of a two
terminal line with having only a person at one end.
Please note it is not applicable to three terminal
lines.
The Trip Test on the UPLC™ works in conjunc-
tion with the local receiver as well as the remote
receiver and transmitter to test the ability of the
system to shift to the trip frequency and receive
the trip frequency at the opposite end.
For 2-frequency FSK systems, the trip test can be
set for a "real" trip or a "checkback" trip. The
"real" trip will produce an output of the receiver
logic TRIP. A "Checkback" Trip setting will pro-
vide only a checkback trip output from the receiv-
er logic, which can be used to pick up an auxiliary
relay or indicating light. Only the "checkback"
trip setting can be used for 3-frequency systems.
7.8.1
Two Frequency Applications
Real Trip Scenario
In this application, the local end, at which you ini-
tiate a Trip Test, will receive a real TRIP as well
as a CHECKBACK TRIP, but the remote end will
only produce a CHECKBACK TRIP. When using
this application the end that initiates the trip would
have to be disconnected from the trip relays.
Refer to the timing diagrams at the end of this
chapter.
When a trip test is initiated, the local transmitter
shuts down for 2 seconds. The remote end receiv-
er will see this as a loss of channel. After 2 sec-
onds, the local transmitter then keys to the trip fre-
May 2012
Chapter 7. Optional Testing Facilities
CAUTION
!
• IF THE UNIT IS SET FOR A REAL TRIP, THEN CAUTION
SHOULD BE TAKEN TO OPEN THE TRIP CIRCUIT PATH SO AS
NOT TO MISTAKENLY TRIP OUT A BREAKER OR LOCKOUT
RELAY ON A DIRECT TRANSFER TRIP SYSTEM.
• THE RECEIVER LOGIC MUST BE SET FOR "GUARD BEFORE
TRIP" LOGIC.
quency for 2 seconds. The remote end recognizes
this as a Trip Test command and the remote
receiver will then produce a CHECKBACK TRIP
and key the remote transmitter to the trip frequen-
cy for 2 seconds. The local end receiver sees that
as a REAL TRIP and produces a TRIP and
CHECKBACK TRIP output from the logic card
and the electromechanical card.
7.8.2 Two Frequency Application
Checkback Trip Scenario
In this application, both the local and remote ends
shift to "checkback" trip. No trip outputs have to
be disconnected.
Refer to the timing diagrams at the end of this
chapter.
When a trip test is initiated, the local transmitter
shuts down for 1.5 seconds. The remote end
receiver will see this as a loss of channel. After 1.5
seconds, the local transmitter then keys to the trip
frequency for 0.5 second. The remote end recog-
nizes this as a Trip Test command and the remote
receiver will then produce a CHECKBACK TRIP
and shut down the remote transmitter for 2 sec-
onds. The remote transmitter is then keyed to the
trip frequency for 0.5 second. This in turn pro-
duces a loss of channel and CHECKBACK TRIP
(without a real TRIP) at the local end.
7.8.3
Three Frequency Applications
Checkback Trip Scenario
In this application, both the local and remote ends
shift to "checkback" trip. No trip outputs have to
be
disconnected.
Both
unblock/POTT) are checked. DTT is low frequen-
cy and unblock/POTT trip is high frequency.
trips
(DTT
&
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