About Soft Starts - Danfoss AK2-SC 255 Reference Manual

About soft starts

Configuring
demand limiting
HVAC
demand limiting
RS.8D.M1.22
The effect of a soft start is to slowly add load to the generator after it starts. If, for
instance, soft start begin level is set to 6, when the generator starts only refrigeration
loads and loads assigned level 7 through 11 will be on. After one minute, if the load is
below the "start shedding at" percentage of maximum emergency load, level 6 will be
turned on. After another minute, the same decision will be made for level 5, and so on
down to level one. If at any time the load reaches the "start shedding at" percentage,
load shedding will begin again until the system reaches the "start restoring at" per-
centage.
One utility meter per AKC 55 will allow configuration for demand limiting. Configur-
ing demand limiting strategy is a two-step process. First you select the meter to be
used for demand limiting and enter the parameters; then select the loads to be shed
for limiting demand and give each a priority.
In order to use demand limiting, you must have a Danfoss-approved utility meter with
Echelon interface and, if you are going to establish both normal and emergency load
limits, you must wire and configure an on/off input for the automatic transfer switch.
In addition, if the site has a coupling switch, you must wire and configure an on/off
input for the coupling switch.
You may wish to read the section "How demand limiting works" that follows the
section "Lighting demand limiting," before you start configuration. Now return to the
Energy menu (one good way is to return to the Main Menu (menu key), select
Energy, then select Demand Limiting. From the Demand Limiting menu, select
Configure. These two screens look like this:
When you put the cursor on Configure, the second page of the Demand Limiting
Menu appears as at left below, offering two choices: Select Units (for HVAC) and
Select Zones (for lighting). Choose Select Units and the screen at right (below)
AK2-SC 255 Reference Manual
"rolling demand" using a "sliding window."
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