Troubleshooting guide

MAGNUM VERSION 8 MANUAL REVISION 3.1
25
UNIT SMOKE UNLDG (20) 6.1.21.
This state is entered when the system is unloading because a smoke alarm sensor has tripped. When this
sensor is on, an error message “OFF-SMOKE ALARM” is generated and the unit state is changed. See
section 6.1.10.
UNIT OFF UNLDING (21) 6.1.22.
This state is entered when the unit has been disabled. It will force a quick unload of the system.
UNIT DMD UNLDING (22) 6.1.23.
This state is only entered when the demand limiting input has been selected. The demand limit sensor
must be selected in the General Information panel under the MAG V8 screen and its type must be “485
Dmd Step”. This input will indicate the maximum number of steps that the unit can run. If this value is less
than the number of steps that are currently on, the unit will unload to meet this value.
UNIT HEAT UNLDING (23) 6.1.24.
This state will be entered and will begin unloading the system if it is in heating mode and the control
temperature is greater than the control temperature Setpoint plus Setpoint #164 “HP CTL ZONE +”
and the system is not already fully unloaded.
UNIT UNLDNG-VFD (24) Only with CENT Software 6.1.25.
This state is entered when it is necessary to unload a centrifugal compressor with a VFD and the
vanes are fully open. The VFD will be modulated down to minimum speed before the vane
positioning is changed.
UNIT LOADNG-VFD (25) Only with CENT Software 6.1.26.
This state is entered when it is necessary to load a centrifugal compressor with a VFD and the
vanes are fully open. The vane positioning will remain the same as the VFD is modulated up to
maximum speed.
6.2. Compressor Control States (number)
All User Logic points can now access the Compressor Control State. The value accessed is the number
listed in parenthesis in the following headings.
The action of the compressor control states may result in an increase or decrease in capacity. The Unit
Control States may affect or change the Compressor Control States or supersede them altogether.
LOST IO LOCKED (0) 6.2.1.
This state is entered when the Capacity Control State is NO RUN- I/O LOST. Resetting the lockout will
move the compressor to the CMP OFF/READY state.
CMP LOCKED OUT (1) 6.2.2.
This state is entered when the Capacity Control State is in UNIT IN LOCKOUT or a safety trip has
occurred for this compressor (Examples of safety Setpoints include #77 “LOW SUCTION” and #81 “HI
DISC PSI”). Lockouts can be reset without authorization from the keypad or MCS-Connect program,
however if the condition causing the lockout has not been corrected, the compressor will again be forced
into the LOCKOUT State.
SWITCHED OFF (2) 6.2.3.
This state is entered when the compressor is off due to the pump down switch being on or the
compressor flow switch being off. In this state the compressor and all related points, including the liquid
line solenoid are off. The compressor will not leave this state unless the pump down switch is turned off. If
the pump down switch is turned off, the compressor state will be changed to the CMP OFF/READY state.
UNLD and PMPDWN (3) 6.2.4.
This state is entered when the pump down switch has been turned on or if this compressor is no longer
Wanted On. The compressor remains on while the liquid line solenoid is closed. This state is active until