AAON RSMZ User Manual

17
RSMZ Technical Guide
SEQUENCE OF OPERATIONS
Alarm Faults
Alarm Faults
Low Suction Pressure Fault
Low Suction Pressure will be ignored for the rst minute of
initial compressor operation. If Suction Pressure is below 95
psig for one minute, the compressor will be turned o and will
be retried after ve minutes.
Compressor 2 Low Suction Pressure Fault
Low Suction Pressure will be ignored for the rst minute of initial
compressor operation. For tandem circuits, if both compressors
are running and Suction Pressure is below 95 psig for one minute,
the second compressor will be turned o and will be retried after
ve minutes.
Unsafe Suction Pressure Fault
Unsafe Suction Pressure Detection will be ignored for the rst 30
seconds of initial compressor operation. If the Suction Pressure
drops below 50 psig for ve seconds, the compressor(s) will be
turned o and will be retried after ve minutes.
High Discharge Pressure Fault
On a single compressor circuit, if the Discharge Pressure rises
above 600 psig, the compressor will be turned o and will be
retried after ve minutes. The compressor will not be reactivated
until the pressure rises above 475 psig.
Compressor 2 High Discharge Pressure Fault
On a tandem compressor circuit, if the Discharge Pressure rises
above 575 psig and both compressors are running, the second
compressor will be turned o and will be retried after ve
minutes.
Compressor 1 Not Running Fault
If Compressor 1 has been activated for at least 45 seconds and
the running verication signal is not active, the compressor
signal will be turned o and will be retried after ve minutes.
For Danfoss VFD compressors, the running verication is sent
from Modbus Communications. For xed On/O compressors,
the running verication is a binary input signal to the module.
Compressor 2 Not Running Fault
If Compressor 2 has been activated for at least 45 seconds and
the running verication signal is not active, the compressor signal
will be turned o and will be retried after ve minutes. For xed
On/O compressors, the running verication is a binary input
signal to the module.
Low Superheat Fault
The low superheat detection will be ignored for the rst two
minutes of initial compressor operation. If the superheat drops
below 4ºF for two minutes, the compressor signal will be turned
o and will be retried after ve minutes.
High Discharge Line Temperature
This sensor is installed for modulating VFD compressors
only. If the Discharge Line Temperature rises above 260ºF, the
VFD compressor will modulate down 1% per second until the
Discharge Line Temperature drops below 260ºF.
If the compressor modulates down to 1800 rpm, the compressor
will be turned o and will be retried if the Discharge Line
Temperature drops below 150ºF and ve minutes has lapsed.
DMQ EXV Sensor Not Detected Fault
If the DMQ EXV Superheat Controller is not detected through
Modbus communications for one minute, the compressor(s) will
be turned o. This fault will be cleared when communication
is reestablished.
Communications Loss Fault
If E-BUS communications are lost for at least 15 seconds, the
compressor(s) will be turned o. If the module is controlling a
Danfoss VFD compressor and the Modbus communication to
the Danfoss VFD compressor is lost for at least 15 seconds, the
compressor will be turned o. This fault will be cleared when
communication is reestablished.
High Superheat Fault
If a compressor is active and the superheat is above 30ºF for 10
minutes or longer, the compressor(s) will be turned o and will
be retried after ve minutes.
High Evaporator Saturation Temperature
Fault
On a tandem circuit, both compressors have to be running to
trigger a fault. A modulating VFD compressor has to be at 100%
to trigger a fault. If the Evaporator Saturation Temperature
rises above 59ºF for the stage up delay plus two minutes, the
compressor will be turned o and will be retried after ve
minutes.

AAON RSMZ Specifications

General

Brand	AAON
Model	RSMZ
Category	Control Unit
Language	English