Rockwell Automation 937CU-DIFRQ_1 Universal Frequency Converter Installation Instructions - Manual (Page 25)

Bul. 937
C Universal Frequency Converter Installation Instructions
Switching Point and Hysteresis
When entering values for the switching point and hysteresis, please note:
•Both values should be entered in the unit that was selected under Unit (Refer to Units). Values
can be entered between 0.001 Hz and 5000 Hz (for non-ex devices: 12 kHz). You can determine the input
limits for a unit other than
Hz by using the conversions given in
Units.
•Since the Universal Frequency Converter internally converts all values into whole mHz (= 0.001 Hz),
rounding errors may occur in values which you enter in rpm, r/sec, l/min, l/h, m3/h, km/h or m/s. If your
application cannot tolerate these small variations in exceptional cases, then select the unit Hz.
•The hysteresis should selected to be > 1 % of the switching point to prevent the relay from fluttering.
•As shown in the illustration of operational behavior in section , in
MAX operating mode, the switching
point - hysteresis value must be > 0, while in the MIN operating mode, the value switching point +
hysteresis  upper limit switching point entry.
All these input limits are automatically assigned by the Universal Frequency Converter.
23