Troubleshooting guide

MAGNUM VERSION 8 MANUAL REVISION 3.1

EXV Maximum Operating Pressure

7.43.3.

Setpoint #199 “MOP TARG PSI” must be active if the suction pressure is to be checked for maximum

operating pressure.

If the suction pressure is above the MOP control zone, then the EXV state will be changed to EXV IS

MOP CLS. The EXV valve opening will be closed by the value in Setpoint #201 with each adjustment.

The ‘Time(sec)’ field of Setpoint #201 will be the delay between making adjustments to the EXV valves. The

EXV will remain in this state until the suction pressure drops below the top of the MOP control zone. At this

point the state will be changed to EXV IS MOP HOLD.

In the EXV IS MOP HOLD state the EXV valve’s opening cannot be increased but it can be closed. The EXV

will remain in this state until the suction pressure drops below the MOP control zone. At that time the EXV

control state will change to EXV IS HOLDING and normal EXV control will resume.

(Refer to section 13 Setpoints #199, #200, and #201)

Tandem EXV Setup

7.43.4.

The Magnum supports tandem EXV control. However a separate compressor must be set up to support

this function. Therefore, the maximum compressors that can be supported with tandem EXV are ten.

The tandem EXV compressors must follow the active compressors in the system.

7.43.4.1. Example: One Compressor with One Step and Tandem EXV’s

In the General Information panel of the MAG V8 screen enter the number of compressors and steps:

In the Circuit Base screen the base compressor information will be entered. The active compressors

information is to be completed as normal and the tandem EXV information will be provided as needed.

Note the Type of LLS cell must be ‘EXV&LLS’ for the active compressor and ‘EXV only’ for the tandem

compressor.

In the next section the EXV Output cell must be set up for both the EXV’s

In the next section the active compressor is associated with its tandem EXV in the ‘Tandem EXV Circuit

#’ cell. Circuit #1 ties to circuit #2, this is the tandem EXV. The Suction Group cells are 1 and 2

respectively.