Rockwell Automation 1902 Syncpro II - Manual (Page 41)

Rockwell Automation Publication 1902-IN001B-EN-E - April 2013 43
Programming SyncPro II Chapter 5
Table 2 - Function Numbers
Set Point 4: Squirrel-Cage Protection Trip Time (at 95% speed)
This time setting determines the maximum length of time the synchronous
motor may run at 95% speed before it is shut down. The squirrel-cage winding of
the synchronous motor is not rated to run the motor continuously even at no
load and therefore must be shut down if synchronism does not occur. Time
should be set to motor manufacturer’s specifications.
Set Point 5: Squirrel-Cage Protection Trip Time (at 50% speed)
It is possible that a synchronous motor can accelerate only to an intermediate
speed and either not accelerate further or take too long to accelerate further due
to overloading. This would cause the squirrel-cage windings to overheat if
allowed to continue unchecked. This setting limits the time that the motor can
operate at 50% speed to the safe maximum recommended by the manufacturer.
Set Point 6: Squirrel-Cage Protection Trip Time (at stall)
In the event that a synchronous motor fails to accelerate at start up it will go into
a stall condition at zero speed. This can occur if the motor is overloaded at start.
The time entered at this set point should be the maximum allowable stall time on
the Squirrel-Cage Winding as defined by the motor manufacturer.
Variable Function Number
t
sp4
Squirrel-Cage Protection Trip Time (at 95% speed)
t
sp5
Squirrel-Cage Protection Trip Time (at 50% speed)
t
sp6
Squirrel-Cage Protection Trip Time (at stall)
f Detected slip frequency
f
sp1
Minimum Percent Synchronous Slip Frequency
f
50%
Squirrel-Cage Protection Trip Frequency
f
sp2
Operating Frequency
4 4 sp
t SP =
5 5 sp
t SP =
6 6 sp
t SP =