Rockwell Automation 1397 Pulse Encoder Interface Installation Inst. - Manual (Page 4)

1397 Pulse Encoder Interface Card 4
1397-5.13 June, 1997
Example
Using a 5,000 RPM motor with a requirement to run as low as 25 RPM —
How to Select the PPR of
a Pulse Encoder
(continued)
Determine the Pulse Encoder’s Minimum PPR Requirement —
PPR
1
= [1]
×
[60] = 120 PPR
———————
25
×
[0.02]
Pick a PPR for the Application — In This Example 500
PPR
1
≤
500
≤
PPR
2
Determine the Maximum Allowable Pulse Encoder PPR —
PPR
2
≤
73,000
×
60
≤
876 PPR
———————
5000
Calculate the Pulse Encoder’s Required Frequency at P.041 [Max Motor Speed] —
Freq
req
= [5,000]
×
[500] = 41.67kHz
————————
60
Confirm That the Pulse Encoder Frequency
≤
80% of the Pulse Encoder’s
Maximum Rated Nameplate Frequency — In This Example 120kHz
41.678k Hz
≤
.8 (120,000)