Future Design MCTB 4.3, Руководство пользователя

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MCTB
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4.2.16 Output 2 Failure Transfer
The output 2 failure transfer setting is used to set the value the output should go to if there is an input failure,
i.e., sensor break. The output can be set for bumpless (-1) operation or a fixed percentage of output (from 0 to
100%) if proportioning or linear control is selected for the output function. When failure transfer is set to
bumpless, the output will remain at its previous percentage of output until the input condition is corrected. Note
that this should not be used for extended periods of time as a runaway condition could occur if separate limit
devices are not installed to ensure safe limits of operation by turning off the system should a limit be exceeded.
If the output function is set as an alarm, the failure transfer can be set to have the output turn on (1) or turn off
(0) when a sensor break occurs.
NOTE: The failure transfer setting is not applicable when the output 2 function is set for event or DC power
supply and does not affect output operation.
4.2.17 Output 2 Low/High Limit Values
The output 2 cycle time can be set when the output 2 function is set for cooling time proportioning control. The
cycle time can be adjusted from 0.1 to 90.0 seconds. For cycle times less than 18 seconds, it is recommended
that the loop control board be ordered with the SSRD drive output for output 2 to extend the life of the control
output.
4.2.18 Output 2 Low/High Limit Values
The output low and high limit values can be set when the output 2 function is set for cooling time proportioning
or linear control. They are used to set the minimum and maximum percentage of the output range for the
installed output type.
For example, the standard range of the mA output is 0-20mA. In order to use the output as a 4-20mA output,
the low limit value would need to be set to 20% (20% of 20ma = 4ma). For the voltage output, the default range
is 0-10VDC. In order to achieve a 1-5VDC output, the low limit would have to be set to 10% (10% of 10VDC is
1VDC). The high limit would then have to be set to 50% in order cut the output span in half to get a maximum
output of 5VDC.
It is recommended that the output low limit be set for 0% when time proportioning is selected as the output
function. Otherwise, the output would continue to cycle on and off even if the control output required by the
PID value is 0%. In the case of time proportioning outputs, the cycle time is used as the range of the output. If
the cycle time were set to 18 seconds, a low limit setting of 10% would equate to a 1.8 second minimum on
time. Thus, even with the PID value calling for 0% output, the output would still cycle 1.8 seconds on and 16.2
seconds off.
4.2.19 Output 3 Function
The Output 3 Function selection is used to configure the loop control board output as an alarm or an event.
The output selections are mutually exclusive, i.e., selecting one will turn off the others. Once the desired
function has been selected, press the “Done” button to set the output function and return to the main Loop
Configuration screen.