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5 - ELECTRICAL CONNECTIONS
5.9 - Speed regulator
The units are equipped with variable speed drives for the
compressors and condenser fans motors. The variable speed
drives are integrated into the electrical cabinets. If the fan motors
are electronically commutated motors (optional EC motors), there
is no corresponding variable speed drive in the electrical cabinet.
The variable speed drive enables the speed of the motors to be
selected by adjusting the voltage and frequency by modulating
the pulse width (PWM).
5.10 - Cabinets for the electrical equipment
The machines are equipped as standard with two cabinets for the
electrical equipment:
A power cabinet for the incoming power supply and the compressor
variable-speed drives.
A control cabinet for the control system elements and the
variable-speed drives and power circuits for the condenser fans
and the water pumps.
Rear section for components with high heat
Support plates for components and separation of air flows
Front section for components with low heat
dissipation
dissipation
The frequency setpoint on the operating range and the status
feedback for the variable speed drives is transmitted by
communication via the internal RS485 Bus using the LEN Protocol
by the "Carrier controller".
For the compressors, the variable-speed drive provides the unit
shut down function via the pressure switches cabled to the
regulator's digital inputs.
In the control cabinet, the components are mounted on a mounting
plate which ensures the flow of cooling air from the heat-dissipating
elements is contained in the area to rear of the cabinet. This design
means that the mounting plate or the casing panel must be
removed to access the equipment which is located in the back of
the panel: transformers, power distribution connections and cooling
fans; refer to the wiring diagram for the unit.
The mounting plate and the casing panel are designed to be easily
removed for servicing operations (see also chapter 13 of this
document).
Overall view of the control cabinet with the casing panel removed:
35
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