Schweitzer Engineering Laboratories SEL-701-1, Instruction Manual

Page: 269 / 452

Date Code 20011009
SEL-701-1 Monitor
SEL
OGIC®
Control Equations and Monitor Logic
Start and Emergency Restart Logic
B.27
Start and Emergency Restart Logic
Figure B.7 shows the logic the monitor uses to initiate motor starts.
Figure B.7 Start Logic.
If the Trip output contact is not asserted, the monitor asserts the START Relay
Word bit in response to any of these conditions:
The Motor Start SEL
OGIC
control equation (STR) result
is true (logical 1).
The Emergency Restart Relay Word bit asserts.
You execute the STR serial port command or a Modbus Start
control command.
The START Relay Word bit remains asserted for 0.5 seconds, unless the monitor
trips. If the monitor trips before the 0.5 second timer expires, the monitor resets the
timer, clearing the START Relay Word bit.
The Motor Start SEL
OGIC
control equation allows you to define a logical
condition that initiates a motor start.
EXAMPLE B.2 Initiating a Motor Start Using a Monitor Contact Input
You can use a monitor contact input such as IN6 to initiate motor
starting. Set the SEL
OGIC
control equation STR = IN6. Connect the
normally open pushbutton contact to monitor terminals C08 and
C09 (IN6). Program an output contact to close when the START
Relay Word bit asserts, as shown in
Program an Output Contact for
Motor Starting on page B.28 . When you push the button, IN6 is
asserted, asserting the START bit, closing the output contact, and
initiating the start.
TRIP
Reset
START
0
0.5 s
STR =
EMRSTR =
START =
TRIP =
Motor Start SEL
OGIC
Control Equation
Emergency Restart SEL
OGIC
Control Equation
Initiate Motor Start Relay Word Bit
Trip Output Contact Is Asserted
STR
EMRSTR
STR Serial Port
Command