12 Rockwell Automation Publication 440R-RM003A-EN-P - July 2021
Chapter 2 CU3 Control Unit
Threshold and Delay
Settings
Both the CU3 control unit and the MSR55P safety relay have a potentiometer
for adjusting the back EMF threshold setting. To access the threshold setting
adjustment in the CU3 control unit, you must open the front cover. The
MSR55P safety relay has the threshold setting adjustment on the front face.
In addition, the MSR55P safety relay has a second potentiometer on the front
face. This potentiometer is for adjusting a delay time from when standstill is
detected to when the outputs are energized. This feature provides additional
assurance that the motor has achieved a steady state speed that is considered
safe.
Terminal Locations and
Panel Space
Figure 2 on page 13 shows the relay sizes and terminal locations. The CU3
control unit has one row of terminals at the top and bottom. The MSR55P
safety relay has two rows of terminals at the top and bottom to accommodate
the features that the CU3 control unit does not have.
Both control units are 45 mm (1.77 in.) wide. The MSR55P safety relay is taller.
To achieve optimal heat dissipation, 50 mm (2 in.) of spacing is recommended
above and below each control unit.
Table 2 - CU3 Catalog Options
Cat. No. Supply Voltage
Standstill Monitoring
Voltage Threshold
Typical Applications
440R-S35001 24V AC/DC
Up to 2.5V Induction motors
440R-S35002 110V AC
440R-S35002 230V AC
Table 3 - MSR55P Catalog Options
Cat. No. Supply Voltage
Standstill Monitoring
Voltage Threshold
Typical Applications
440R-S35011 24V DC
20...400 mV Induction motors
440R-S35012 115V AC
440R-S35013 230V AC
440R-S35014 24V DC
200 mV…4V
Servo (permanent magnet)
motors
440R-S35015 115V AC
440R-S35016 230V AC
To Next Page
Loading...
