Honeywell EXCEL 5000 User Manual page 72

ALPHABETIC REFERENCE
74-5577–33 (US)
EN2B-0184 GE51 R0518 (Europe)
Outputs Out = output (Parameter P1 controls action of output, 0 = direct action, 1 = reverse
action)
Rmp = start ramp value (0-100 pct)
The output start value input controls the initial value of the output at the beginning of
the start ramp period. This value is also present at the output when the enable input
is off.
The ramp output goes from 0 to 100 during the start-up ramp period. (Provided for
diagnostic use, if desired.)
The start ramp time input sets the duration of the start ramp by controlling the value
of internal Parameter P7. You should not directly set the value of P7. If you enter a
value for SRT in CARE, software creates an M0 parameter.
The integral component is not saved directly. Instead, the proportional and
derivative values are used to determine what the integral component should be to
produce the current output value. If the output falls to minimum or rises to maximum
or is overridden by the auxiliary input, the integral component is calculated so that it
is consistent with the actual output.
The following diagram illustrates the two outputs, OUT and RMP, of EPID.
Example 1 EPID can control a variable speed drive to maintain duct static pressure. The OSV is
set to 25 percent and the SRT is set to 180 seconds. When enabled, the drive starts
at 25 percent and slowly increases toward 100 percent taking at least 180 seconds
to do so. If duct static rises (as it should), it might take less time to arrive at setpoint.
Example 2 EPID can control a heating coil valve, mixing dampers, and a cooling coil valve in
sequence. The SRT is set to 300 seconds and the OSV is set to 33 percent
(assuming equal split in the sequencing setup) so that, on start-up, all valves and
dampers are closed. Then the output can slowly ramp toward 0 percent on a call for
heating or toward 100 percent on a call for cooling. It takes at least 300 seconds to
fall from 33 percent to 0 percent on a call for heating or to rise from 33 percent to
100 percent on a call for cooling. Since the cooling side traverses two parts or the
sequencing range, only half the SRT is seen by the damper or valve. Keep this in
mind when using sequencing.
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EXCEL CARE CONTROL ICONS