Danfoss VLT CDS 303 User Manual

25-22 Fixed Speed Bandwidth [%]
Range: Function:
Emergency Stop (Coast/Coast inverse Command)
for the Cascade Controller.
25-23 SBW Staging Delay
Range: Function:
60
sec.*
[0-3000
sec.]
Immediate staging of a xed speed
compressor is not desirable when a
momentary pressure drop in the system
exceeds the Staging Bandwidth (SBW).
Staging is delayed by the length of time
programmed. If the pressure increases to
within the SBW before the timer has elapsed,
the timer is reset.
SBW (27-20)
SBW (27-20)
Setpoint
175ZA672.12
SBW staging-vertr. (27-23)
Figure 6.28 SBW Staging Delay
25-24 SBW Destaging Delay
Range: Function:
60
sec.*
[0-3000
sec.]
Immediate destaging of a xed speed
compressor is not desirable when a
momentary pressure increase in the system
that exceeds the Staging Bandwidth (SBW).
Destaging is delayed by the length of time
programmed. If the pressure decreases to
within the SBW before the timer has elapsed,
the timer is reset.
175ZA671.11
(27-24) SBW destage delay
SBW
SBW
Setpoint
(27-20)
(27-20)
Figure 6.29 SBW Destaging Delay
25-25 OBW Time
Range: Function:
60
sec.*
[0 –
300
sec. ]
Staging a xed speed compressor creates a
momentary pressure peak in the system, which
might exceed the Override Bandwidth (OBW). It is
not desirable to destage a compressor in
response to a staging pressure peak. The OBW
Time can be programmed to prevent staging
until the system pressure has stabilized and
normal control established. Set the timer to a
value that allows the system to stabilize after
staging. The 10 second factory setting is
appropriate in most applications. In highly
dynamic systems, a shorter time may be
desirable.
Setpoint
SBW (27-70)
OBW (27-71)
SBW (27-70)
OBW (27-71)
Actual head
OBW timer (27-25)
130BA370.11
Figure 6.30 OBW Time
25-27 Stage Function
Option: Function:
[0] * Disabled
[1] Enabled If the Stage Function is set to [0] Disabled,
parameter 25-28 Stage Function Time will not be
activated.
25-28 Stage Function Time
Range: Function:
10
sec.*
[0 –
300
sec.]
The Stage Function Time is programmed to
avoid frequent staging of the xed speed
compressors. The Stage Function Time starts if it
is [1] Enabled by parameter 25-27 Stage Function
and when the variable speed compressor is
running at parameter 4-13 Motor Speed High
Limit [RPM] or parameter 4-14 Motor Speed High
Limit [Hz] (or at parameter 4-11 Motor Speed Low
Limit [RPM] or parameter 4-12 Motor Speed Low
Limit [Hz] if parameter 7-30 Process PID Normal/
Inverse Control is programmed to Inverse), with
at least one xed speed compressor in the stop
position. When the programmed value of the
timer expires, a xed speed compressor is
staged.
Parameter Descriptions Operating Instructions
MG34M422 Danfoss A/S © Rev. 2013-07-03 All rights reserved. 115
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Danfoss VLT CDS 303 Specifications

General

Brand	Danfoss
Model	VLT CDS 303
Category	DC Drives
Language	English