Troubleshooting guide

MAGNUM VERSION 8 MANUAL REVISION 3.1
71
7.71. Tonnage and KW Information (8.03-F)
KW Sensors 7.71.1.
Unit KW – virtual sensor that calculates the unit Kilowatt usage. The Power Factor (PF) sensor must be
selected in the ‘Temp. / GPM / CFM / Pwr Factor SI’ cell.
Kw = Amps * Volts * Power Factor * Internal Constant of .00173
Power Factor – Virtual sensor tied to a Setpoint where a manual value of the unit’s power factor may be
defined. If not specified, a hardcoded value of .85 will be used.
Unit Volts – Voltage being supplied to the unit. This sensor can be an actual voltage sensor or virtual point
that reads a static value from a Setpoint.
Unit Amps – Sensor reading the amperage of the entire unit. If no total unit amp sensor is specified, the
software will automatically sum all the individual compressor amp sensors to approximate the unit amps.
Tonnage Sensors 7.71.2.
Unit Tons – a virtual sensor that calculates the unit tonnage. The Unit Flow (GPM or CFM) sensor must be selected in
the ‘Temp. / GPM / CFM / Pwr Factor SI’ cell, and the Enthalpy Differential or Temperature Differential sensor (air and
water cooling systems respectively) must be selected in the ‘Humd. SI / Temp. Diff. / Enthal. Diff.’ cell. Also the correct
values must be placed in the ‘Multiplier’ and ‘Divisor’ cells depending on the type of system; 45 and 10 respectively for
air, 1 and 24 respectively for water (refer to pictures above).
Tonnage (air) = Flow (CFM) * Enthalpy Differential * 4.5
Tonnage (water) = Flow (GPM) * Temperature Differential / 24
Unit Flow (GPM or CFM) – Gallons per minute (for water) or cubic feet per minute (for air). This can be an actual flow
sensor or virtual point that reads a static value from a Setpoint. NOTE: It is essential for a correct calculation that this
sensor must be configured so as to have no decimal places.
Water In and Out Temperatures – (Water only) Temperature sensors for Water In and Out.
Temperature Differential – (Water only) User logic that subtracts Water Out Temperature from Water In
Temperature.
Temp Diff = Water In – Water Out
Supply and Return Humidity – (Air only) Humidity sensors for Return and Supply air.
For Air Cooling Systems
For Water Cooling Systems