S (RPS)
T(s)
Figure 14: Start/Stop/Ramp setting
Danfoss
OE-000091
0.67s
0
30
S (RPS)
Start delay duration 60s
Starting ramp time
default 45rps/s
Ramp 1 r
amp up time
default 0.5r
ps/s*
Target speed
Target speed
*can be adjusted properly according to application
Ramp 1 ramp down time
default 0.5rps/s*
Stopping ramp
time default 45rps/s
T(s)
Speed
Time
Short cycle protection
Minimum run time is necessary to ensure proper oil return to the compressor. A 3 minute minimum run time is
usually recommended but some systems may require more time to establish proper superheat and stable oil return.
Additionally, compressor must not exceed a maximum of 12 starts per hour. 12 starts per hour must not be
considered as an average, this is the maximum number of starts acceptable to keep a good regulation accuracy
during low load. Short cycle protection can be done either by the drive or the unit controller. The following table
describes the parameters to adjust depending on which short cycle protection is selected.
Table 15: Short cycle protection
Drive parameters
Description
Value
Default
Short cycle protection is done by unit controller
28.00
Short cycle protection
Short cycle protection done in unit controller: (preferred option)
Disable
Enable
Short cycle protection is done in drive
(1)
28.00
Short cycle protection
Short cycle protection done by the drive.
Enable
Enable
28.01
Interval between stop and start Start command is ignored until the timer (10s) has elapsed. Only
then, can the compressor start.
10s
10s
(1)
If short cycle protection enabled in drive, the start will be ignored during minimum stop time.
(1)
If short cycle protection enabled in drive, the start will be ignored during minimum stop time.
The diagram below demonstrates how the function works:
Scroll compressors, VCH115 | Frequency converter
© Danfoss | Climate Solutions | 2023.08
AB392939083370en-000202 | 28