CHAPTER 5: SETPOINTS
MM300 MOTOR MANAGEMENT SYSTEM – INSTRUCTION MANUAL
Range: 0 to 125 seconds in steps of 1
Default: 1 second
The value specified by this setpoint is the time during which, the motor will be supplied
with the reduced voltage through an autotransformer. When this time expires, contactor
B will close and supply the full voltage to the motor.
Range: 1S-2S, 2S-1S
Contactors 1S and 2S are closed in a sequence with a 20 millisecond delay. Contactor
Sequence setpoint selects the order of closing.
An additional two setpoints have to be configured in order to make the element work
properly: Contactor C Status and Contactor C. Refer to section
on page 5-22. The selections made there also assigns two system messages
Open Ctrl Cct and Welded Contactor to the status of contactor 2S.
It is recommended to check the specifications of the autotransformer used for this
application and adjust the MM300 setpoint Starts/Hour Limit if necessary [Path: Home >
Setpoints > Control > Inhibits].
Pre-contactor is omitted on forced starts (for example, UVR Immediate, External Start).
Otherwise, type A forced starts operate in the same fashion as other type A starts, with the
transfer to full voltage occurring when the transfer time expires. Type B forced starts are
not supervised by this starter transfer timer - any external type B starting circuit must itself
respect full voltage starting restrictions.
The following table shows the I/O names used in Autotransformer closed transition starter.
It also shows connections between contactor, inputs/outputs and internal flags/operands
driving these outputs.
Contactor A Relay
Contactor B Relay
Contactor C Relay
Assignable (default: N/A)
Autotransformer closed transition starter is a reduced voltage starter.
The expansion I/O module type C, D or E must be properly installed when the
Autotransformer closed transition starter is used. Three motor contactors R, 1S and 2S
each controlled by a separate MM300 output relay are used to perform this function. There
are two options of this starter: 1S-2S and 2S-1S. Each one offers a slightly different
sequence of contactors operation. The description of both sequences is given as follows:
1S-2S start sequence:
Start A command received by the MM300 (serial, digital input or faceplate).
Wait for the time set in Pre-Contactor Time setpoint.
Close and maintain contactor 1S.
Wait until contactor 1S closed status is received, then close and maintain contactor
2S. Reduced voltage is applied to the motor.
Wait for the time set in the Transfer Time setpoint.
Open Contactors 1S.
Wait until contactor 1S open status is received.
Close and maintain contactor R. Full voltage is applied to the motor.
on page 5-20and
Status contact input
Assignable (default: N/A)