Page 6-12
MPS Motor Protection System Rev. 6-F-022117
Starter Functions
6.11 SOFT-START-WITH-BYPASS STARTER
Sequence: Fig. 6.5
Connection: Fig. 6.19
Current Transfer: Available
START1 or START2 initiates the starting sequence by
activating Starter RLYA. Starter RLYB activates after the
Stage1 Delay to close the bypass contactor.
Although RLYA Status can be selected as a digital
input, it is not usually available for this starter.
For a soft-start where the bypass function is included, a
bypass signal from the soft-start can be used as an input to
the MPS. There are two solutions:
1) This option coordinates the MPS Starter RLYB
signal with the soft-start and ensures the status
input does not validate prior to the intended time.
Assign an MPS output relay with the Starter
RLYB function as per Fig. 6.19. Connect this
output-relay contact in series with the bypass
contact from the soft-start (K1a) and connect this
signal to a digital input programmed as RLYB
Status. Set the Stage 1 Delay longer than the
soft-start bypass time.
2) This option uses a digital input programmed as
Trip1 in conjunction with the MPS trip-bypass
feature. Connect the bypass signal from the soft-
start to a digital input assigned as Trip1. Enable
Trip Bypass and set the Bypass Delay longer than
the start time of the soft-start. Note that this
feature is based on current and during a stop
requires the input to remain valid until current is
not detected. If the soft-start has a ramp-down
feature, set the INx Trip Delay greater than the
ramp-down time to prevent a trip when the soft-
start stops. See Section 4.2.8.
6.12 REACTOR OR RESISTOR OPEN-TRANSITION
STARTER
Sequence: Fig. 6.6
Connection: Fig. 6.16
Current Transfer: Available
START1 or START2 activates Starter RLYA for the
duration of the Stage1 Delay. After Starter RLYA de-
activates for the Stage2 Delay, Starter RLYB activates.
6.13 TWO-WINDING STARTER
Sequence: Fig. 6.6
Connection: Fig. 6.20
Current Transfer: Available
This starter is an open-transition starter for two-
winding motors that run with only one winding energized.
START1 or START2 activates Starter RLYA for the
time specified by the Stage1 Delay. After Starter RLYA
de-activates for the Stage2 Delay, Starter RLYB activates.
This starter requires two full-load current set points.
FLA Rating 2 is the full-load current for the starting
connection (Starter RLYA) and FLA Rating is the full-load
current for the running connection (Starter RLYB).
6.14 WYE-DELTA OPEN-TRANSITION STARTER
Sequence: Fig. 6.7
Connection: Fig. 6.21
Current Transfer: Available
START1 or START2 initiates the sequence. Starter
RLYC activates to close the neutral contactor (K3).
Starter RLYB activates the wye contactor (K2) after the
Stage1 Delay. Starter RLYC de-activates to open the
neutral contactor after the Stage2 Delay and Starter RLYA
activates to close the delta contactor (K1) after the Stage3
Delay. Stage-1 and Stage-3 delays are contactor-transfer
times and should be set in the range of 0.1 to 0.5 seconds.
Locate CT’s on the line side of the starter.
This starter uses two full-load current settings. Set FLA
Rating to the delta full-load current and FLA Rating 2 to
the wye full-load current.
FIGURE 6.19 Soft-Start-With-Bypass-Starter
Connection.
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