GE Power Management
ALPS Advanced Line Protection System
1-25
1 PRODUCT DESCRIPTION
1.8 PROTECTION SCHEMES
1
1.8.3 PERMISSIVE UNDERREACH TRANSFER TRIP (PUTT)
Figure 1–12: PUTT LOGIC DIAGRAM on page 1–29 is the logic diagram for the PUTT scheme. This scheme requires Zone
1 as well as overreaching zone functions. Zone 1 trips directly via OR1, AND4, OR25, OR3, OR4, AND3, OR13, AND13,
OR7, and AND7 and keys the transmitter to the trip frequency via OR5. Tripping for internal faults not seen by the Zone 1
functions occurs when an overreaching function operates and the receiver(s) produce an output, satisfying the input condi-
tions of the comparator, AND407.
The considerations for receiver connections for a three-terminal line application and 52/b contact keying of the transmitter
with one end open are different from those described above under the POTT1 scheme. As with a POTT1 scheme, a PUTT
three-terminal line application requires two receivers and one transmitter at each terminal, with each frequency-shift trans-
mitter operating at a different frequency. However, the two receivers are ORed together at OR21, rather than ANDed
together as with a POTT1 scheme. This is necessary since the Zone 1 functions at only one end of the three-terminal line
may respond for an internal fault.
For a three-terminal PUTT application, do not use 52/b contact keying of the transmitter. Because the two receivers are
ORed together, a continuous trip signal sent from the open end, when only one end is open, results in over-tripping for
external faults within the reach of the pilot overreaching functions. Unfortunately, this means a portion of the line is not pro-
tected by the pilot scheme. In the ALPS, 52/b contact keying of the transmitter is automatically prevented if PICKSCHEME
= 2 [PUTT] and NUMRCVR = 2 [2 RCVRS], as indicated in Figure 1–12: PUTT LOGIC DIAGRAM by the link between
AND5 and OR5. 52/b contact keying of the transmitter should be used for a two-terminal PUTT application.
Figure 1–11: INTERCONNECTION DIAGRAM FOR PUTT/POTT WITH NS40A
(+) BATTERY
(-) BATTERY
T B 1
( R E C E I V E R
O U T P U T )
K 3
( S W I T C H E D P O S I T I V E B A T T E R Y )
( S W I T C H E D N E G A T I V E B A T T E R Y )
12
25
60
11
59
B 2 1
B 5
K T 1
K E Y T R A N S M I T T E R
D 1 8
D 2
C C 1
( R E C E I V E D
T O N E )
A L P S
A L P S S E T F O R P O T T S C H E M E
P I C K S C H E M E = 1 ( P E R M I S S I V E O V E R R E A C H T R A N S F E R T R I P )
T Y P E N S 4 0 A
(WITH RCVR OUTPUT 'T')
I N T E R C O N N E C T D I A G R A M
F O R P O T T S C H E M E
U S I N G N S 4 0 A A U D I O T O N E S E T
A N D
A L P S R E L A Y S Y S T E M
24
1
2
U 9
K E Y T R A N S M I T T E R
K E Y
T R A N S M I T T E R
T O T R I P
S H O W N F O R T H E D E F A U L T
A L P S I / O A S S I G M E N T S
