Catalogue

54 WSHP-PRC020D-EN
Controls
High and Low Pressure Safety Controls
TheTracer ZN510 controller detects the state of the high pressure or low pressure switches. When
a fault is sensed by one of these switches, the corresponding message is sent to the controller to
be logged into the fault log. When the circuit returns to normal, the high pressure control and low
pressure control automatically reset. If a second fault is detected within a thirty-minute time span,
the unit must be manually reset.
Random Start
To prevent all of the units in a building from energizing major loads at the same time, the controller
observes a random start from 0 to 25 seconds.This timer halts the controller until the random start
time expires.
Reversing Valve Operation
For cooling, the reversing valve output is energized simultaneously with the compressor. It will
remain energized until the controller turns on the compressor for heating. At this time, the
reversing valve moves to a de-energized state. In the event of a power failure or controller OFF
situation, the reversing valve output will default to the heating (de-energized) state.