Danfoss ECL Comfort 310 Operating Manual page 23

Operating Guide
2.5.3 Electrical connections, safety thermostats, in general
See also the Mounting Guide (delivered with the application key)
for application specific connections.
The connection diagrams show various solutions / examples:
Safety thermostat, 1–step closing:
Motorized control valve without safety function
Safety thermostat, 1–step closing:
Motorized control valve with safety function
Safety thermostat, 2–step closing:
Motorized control valve with safety function
Danfoss District Energy
ECL Comfort 310, application A368
When ST is activated by a high temperature, the safety circuit in the
motorized control valve closes the valve immediately.
When ST1 is activated by a high temperature (the TR temperature), the
motorized control valve is closed gradually. At a higher temperature
(the ST temperature), the safety circuit in the motorized control valve
closes the valve immediately.
VI.LG.J3.02 DEN-SMT/DK 23