Page 6-2
MPS Motor Protection System Rev. 6-F-022117
Starter Functions
inputs can be programmed to monitor contactor status.
Contactor status corresponding to Starter RLYA, Starter
RLYB, Starter RLYC, and Starter RLYD outputs are
designated as RLYA Status, RLYB Status, RLYC Status,
and RLYD Status. The MPS will issue a Trip1 and
indicate Relay Status Trip if the status contact does not
follow within 500 ms of the command to operate the
respective relay output. In addition, a transition must not
occur prior to its intended time.
When the starting sequence is complete, contactor
status is checked every 500 ms and a Relay Status Trip
will occur if the status changes.
NOTE: Relay Status is not checked when the starter is in
the stopped state.
The Start Time set point is the maximum start time
allowed. The starting process will terminate and generate
a Trip1 unless current is between 1.5 x (CT-Primary
Rating / FLA) and 125% FLA when the Start Time timer
times out.
In reduced-voltage-starting applications, the MPS can
use time-based or current-based transfer from the starting
to the running connection. The transfer type is selected as
Time Transfer or Current Transfer using the Transfer
Type menu.
When Current Transfer is selected, the start-connection
delay (Stage 1 Delay or Stage 2 Delay, see Table 6.2 and
Figs 6.5, 6.6, 6.7, and 6.8) defines the minimum starting-
connection time. The transfer to the run connection
occurs when the start-connection delay has expired and
current is below the Transfer Current. When current is
above the Transfer Current, the transfer will be delayed
up to the maximum time defined by the Start Time. If
current is below 1.5 x (CT-Primary Rating / FLA) when
the start-connection delay expires or if the Start Time is
exceeded, the MPS will issue a Trip1 and indicate Starter
Trip.
When Time Transfer is selected, the start-connection
delay set point (Stage 1 Delay or Stage 2 Delay) is used to
determine the transfer time. Transfer to the run
connection occurs after the start-connection delay has
expired.
In both current- and time-transfer modes, the MPS will
issue a Trip1 and indicate Starter Trip if load current is
above 125% FLA or below 1.5 x (CT-Primary Rating /
FLA) when the Start Time expires. The Start Time set
point must be long enough to allow the starting sequence
to complete and for the motor current to drop below 125%
FLA.
Table 6.2 summarizes starter types and shows which
starter set points are active.
The backspin timer is available when a delay is
required between starts. The backspin timer is enabled in
the BkSpin En/Disable menu, and the delay time is set in
the Backspin Delay menu. The backspin timer is
activated by a STOP or when supply voltage is cycled on
the MPS. While the backspin timer is on, the Backspin
Timer On message is displayed in the Status Message
menu and starts are not allowed.
The connection diagrams, Figs. 6.9 to 6.23, show
typical control circuits with 120-Vac contactor coils and
the 24-Vdc source on the MPS-CTU used for status
contacts. Other supply voltages can be used within the
limits of the digital-input and relay-contact ratings. The
use of status contacts is optional.
NOTE: Stop and start control, electrical interlocks, and
mechanical interlocks are not shown in connection
diagrams.
NOTE: Connection diagrams show typical output relay
assignments that must be set using the Setup ⏐ Relay
Outputs ⏐ Relay x ⏐ Relay x Function menu.
NOTE: To cancel a long backspin time, enter new backspin
parameters and restart the MPS using the Setup | System
Config | Maintenance | Restart MPS-CTU menu or cycle
supply voltage.
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