Future Design MCTB 4.3, Руководство пользователя

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MCTB
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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 for on-off control, the failure transfer can be set to have the output turn on (1) or turn
off (0) when a sensor break occurs.
4.2.12 Output 1 ON-OFF Control Hysteresis
The output 1 on-off control hysteresis can be set when the output 1 function is set for heating or cooling on-off
control. It is used to eliminate rapid cycling of the control output by applying a safe-sided dead band to the
control output. When the control set point is exceeded, the output will turn on. The output will not turn off until
the process rises above (for heating) or falls below (for cooling) the set point by the hysteresis value.
The hysteresis can be set from a minimum of 0.1 to a maximum of 50.0 for units of degrees Centigrade and to
a maximum of 90.0 for units of degrees Fahrenheit and when a linear input type is used.
4.2.13 Output 1 Cycle Time
The output 1 cycle time can be set when the output 1 function is set for heating or 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 1 to extend the life
of the control output.
4.2.14 Output 1 Low/High Limit Values
The output low and high limit values can be set when the output 1 function is set for heating or 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.
4.2.15 Output 2 Function
The Output 2 Function is used to set the mode of operation for the secondary control output of the loop control
board.
NOTE: The output function must be set to match the type of output ordered on the loop control board. Relay,
triac and SSRD output types are used for proportioning control, alarm or event outputs. The isolated
VDC and mA output types are used for linear control.