WEG CFW501 V1.8X, Programming Manual, Page: 159 / 192

HVAC Functions
CFW501 | 18-1
18
18 HVAC FUNCTIONS
The CFW501 frequency inverter is an optimized device for use in heating, ventilation and air conditioning applications,
that is, the HVAC market. As a result, some common functionalities/protections for this market sector were added,
such as:
„
Automatic energy saving.
„
Short cycle protection.
„
Dry pump.
„
Broken belt.
„
Filter maintenance alarm.
„
Main PID controller for motor control.
„
Sleep mode for main PID.
„
External PID controller.
NOTE!
The specific functions for HVAC present on the CFW501 can only be activated with the connection of
the HVAC plug-in module (CFW500-CRS485). Other plug-in modules can be used, but in this case
the HVAC application must be shut down by using parameter P1001.
NOTE!
The dry pump, broken belt, filter maintenance alarm, main PID controller, sleep mode for main PID
and external PID controller functions are implemented on SoftPLC and will only be valid with the
CFW500-CRS485 plug-in module. Otherwise, with the HVAC application active (P1003 = 1), the
inverter will show fault F0773.
NOTE!
One part of the HVAC functions is directly implemented on the CFW501 firmware and the other part
on the SoftPLC program; in this case the related parameters are in the range starting from P1010.
Thus, by setting P1003 = 0, those functions on SoftPLC will be disregarded.
18.1 ENERGY SAVING
The efficiency of a machine is defined as being the ratio between the output mechanical power and the input
electrical power. Remember that the mechanical power is the product between torque and rotor speed, and that
the input electric power is the sum of the output mechanical power and the motor losses.
In the case of the three-phase induction motor, the optimized efficiency is achieved with ¾ of the rated load. In
the region below this point, the Energy Saving function has its best performance.
The Energy Saving function acts directly on the voltage applied on the inverter output; thus, the flux relationship
delivered to the motor is changed so as to reduce the motor losses and enhance the efficiency, consequently
reducing consumption and noise.
The function will be active when the motor load is below the maximum value (P0588) and the speed is above the
minimum value (P0590). In addition, in order to prevent the stalling of the motor, the applied voltage is limited to
a minimum acceptable value (P0589). The parameter group presented in the sequence defines those and other
characteristics necessary for the energy saving function.