Sel 751A - Page 338

7.20
SEL-751A Relay Instruction Manual Date Code 20100129
Communications
SEL ASCII Protocol and Commands
When parameter p is a ramp function, the device displays the following
message during the test:
Ramping Analog Output at xx.xx [units]/min; full scale in
y.y minutes. Press any key to end test
For either mode of operation (percentage or ramp), when the time expires, or
upon pressing a key, the analog output port returns to normal operation and the
device displays the following message:
Analog Output Port Test Complete
Example 1
The following is an example of the device response to the ANA command in
the percentage mode. For this example, we assume the analog output signal
type is 4–20 mA, and we want to test the analog output at 75 percent of rating
for 5.5 minutes. To check the device output, calculate the expected mA output
as follows:
To start the test, enter ANA A0301 75 5.5 at the Access Level 2 prompt:
=>>ANA A0301 75 5.5 <Enter>
Outputting 16.00 mA to Analog Output Port for 5.5 minutes.
Press any key to end test
Example 2
The following is an example of the ramp mode when the analog output signal
type is 4–20 mA for a 9.0 minute test.
To check the device output, calculate the current/time (mA/min) output as
follows:
To start the test, enter ANA AO301 R 9.0 at the Access Level 2 prompt:
=>>ANA AO301 R 9.0 <Enter>
Ramping Analog Output at 1.78 mA/min; full scale in 9.0 minutes.
Press any key to end test
where:
xx.xx
is the calculation based upon range/time t
[units]
is either mA or V, depending on the channel type setting
y.y
is the time in minutes
Output 20.00 mA 4.00 mA–()
75
100
---------
• 4.00 mA+ 16.00 mA==
Output
20.00 mA 4.00 mA–
9.0 min
---------------------------------------------------
1.78 mA/min==