Rockwell Automation 1397 AC Tachometer Interface Card - Manual (Page 2)

2 Allen-Bradley 1397 AC Tachometer Interface Card
How to Select an AC
Tachometer Before installing the AC Tachometer Interface Card, the tachometer’s
maximum AC output voltage and the card’s maximum DC output voltage
must be calculated. Performing these calculations will assure:
•
That the correct AC tachometer is selected.
•
That the correct drive Regulator Board settings are made.
•
That the Tachometer Interface Card is wired correctly.
Step 1 – Determine the Tachometer’s Maximum AC Output Voltage
As listed in the card’s specifications; at the application’s maximum motor
RPM, voltage at the input of the AC Tachometer Interface Card must not
exceed 275V AC rms.
Step 2 – Determine the Card’s Maximum DC Output Voltage
Example
An RE-045F Reliance Tachometer is used in an application that has a
required maximum motor speed of 2500 RPM. An RE-045F Tachometer
has a nameplate output voltage of 45V AC (+10V AC/–5V AC) / 1000.
Determine the Card’s Maximum AC Input Voltage
Determine the Card’s Maximum DC Output Voltage
VAC
in
= [Tach
volt
x N
max
]
1000
where:
VAC
in
= The Interface Card’s Maximum AC
Input Voltage.
Tach
volt
= P.047 [Anlg Tach V/1000]. The
Tachometer’s Nameplate Volts/1000
RPM Rating.
N
max
= Required Maximum Motor RPM for
the Application.
VDC
out
= VAC
in
x 0.9 where:
VDC
out
= The Interface Card’s Maximum DC
Output Voltage.
VAC in = The Interface Card’s Maximum AC
Input Voltage
VAC
in
= [(45 + 10) x 2500]
1000
VAC
in
= 137.5V AC
VDC
out
= 137.5V AC x 0.9
VDC
out
= 123.75V DC