ABB RET650 Applications Manual page 228

Section 11
Control
222
b
URAISE/ULOWER
tTCTimeout
TCINPROG
IEC06000482 V2 EN-US
Figure 81: Timing of pulses for tap changer operation monitoring
pos Description
a Safety margin to avoid that TCINPROG is not set high without the simultaneous presence of an
URAISE or ULOWER command.
tPulseDur .
b Time setting
c Fixed extension 4 sec. of
tStable
d Time setting
e New tap position reached, making the signal "tap change in progress" disappear from the tap
changer, and a new position reported.
f The new tap position available in TCMYLTC or TCLYLTC.
g Fixed extension 2 sec. of TCINPROG, made internally in TCMYLTC or TCLYLTC function.
h Safety margin to avoid that TCINPROG extends beyond
The first use is to reset the Automatic voltage control for tap changer function
TR1ATCC for single control and TR8ATCC for parallel control as soon as the
signal TCINPROG disappears. If the TCINPROG signal is not fed back from the
tap changer mechanism, TR1ATCC or TR8ATCC will not reset until tTCTimeout
has timed out. The advantage with monitoring the TCINPROG signal in this case is
thus that resetting of TR1ATCC or TR8ATCC can sometimes be made faster,
which in turn makes the system ready for consecutive commands in a shorter time.
The second use is to detect a jammed tap changer. If the timer tTCTimeout times
out before the TCINPROG signal is set back to zero, the output signal TCERRAL
is set high and TR1ATCC or TR8ATCC function is blocked.
The third use is to check the proper operation of the tap changer mechanism. As
soon as the input signal TCINPROG is set back to zero TCMYLTC or TCLYLTC
function expects to read a new and correct value for the tap position. If this does
not happen the output signal CMDERRAL is set high and TR1ATCC or TR8ATCC
function is blocked. The fixed extension (g) 2 sec. of TCINPROG, is made to
prevent a situation where this could happen despite no real malfunction.
c
a
tPulseDur , made internally in TCMYLTC or TCLYLTC function.
1MRK 504 169-UEN A
g
e f
h
d
IEC06000482_2_en.vsd
tTCTimeout .
Transformer protection RET650 2.2 IEC
Application manual