Danfoss AK-SM 850 - Master Control Functions; Rail Heat

This section will discuss rail heat control, schedules, HVAC, and
lighting. Please refer to this section when conguring more
advanced areas of your AK-SM.
Rail Heat
The AK-SM can be used to manage the energy output to the case
trim heaters (Rail Heat). There are dierent ways to approach
the solution to rail heat control, listed below are three main
possibilities.
1 - Use a Night Setback Schedule
Many Danfoss controls have a function whereby the output to
the rail heat elements can be pulsed in a percentage of time
ratio. If set in the controller, the night setback signal from the
AK-SM will allow the controller to vary the output depending
on the time period. Consult specic controller manual for
more details
2 - Use AK I/O relays to control rail heater connections
(using ‘Calculated’ or physical Dew point)
By means of utilizing temperature and relative humidity
sensors the AK-SM can calculate the relative Dew point. Based
on this Dew point reference and against a set point the output
to the rail heat elements can be controlled. This represents
‘tighter’ control based on the calculated Dew point.
3 - Use Adaptive Rail heat control
Adaptive rail heat is a feature that groups together a
collection of compatible evaporator controllers that receive
signals of the current calculated dew point from an installed
dew point / temperature sensor. The installed humidity /
temperature sensor connects to the AK-SM (via I/O) and the
resulting calculated dew point value is sent to the connected
evaporator controllers
From the Control screen navigate to Refrigeration then Rail Heat
(Conguration->Refrigeration->Rail Heat)
Master Control Functions
(Energy saving features, scheduling and load shedding
conguration)
36 User Guide Lit. no. USCO.PI.R1.E1.02 © Danfoss 07-2013 AK-SM 850