Table of Contents
Advertisement
9.15 - service valve (option 92)
The unit can be equipped with optional service valves to
facilitate maintenance and repair operations.
If option 92 is ordered, each refrigerant circuit will be
supplied with shut-off valves on the compressor economiser,
discharge and suction lines.
ATTENTION: The compressor suction valve must be
used without pressure difference at the terminals. If there
is a pressure difference, leak-tightness at the valve may be
lost and the valve can even fail altogether.
Equal pressure
9.16 - Variable frequency drive
The 30XAV-ZE units are fitted with a variable frequency
drive that allows adjustment the capacity of the
compressor by varying the speed of the motor within the
frequency range of 27.5-60 Hz.
Variable speed is produced by generating a controlled
voltage waveform, on which both frequency and voltage
are adjustable (via Pulse Width Modulation).
The compressor start-up/stop and the frequency setpoint
(within the acceptable range) is managed through RS485
communication via LEN Protocol by the "Carrier
Controller".
One of the other features of the "variable frequency
drive" is to ensure the safety stop function of the unit via
HP switches wired to the digital inputs. This safety function
follows the EN ISO 13849-1 standard in compliance with
the requirements of the directive of equipments under
pressure (DESP).
33
Advertisement
Table of Contents
