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Operation and Maintenance
Envistar Top 04-21
DSET.220501.07.en
Continuous product development may give rise to specification changes without notice.
Cooling function
For integrated control equipment (MX), the cooling unit is interlocked across
the ventilation unit. If any of the fans stop, the cooling unit will also stop. The
interlock and demand signal is sent via Modbus.
For external control equipment (US, UC, MK), the interlock signal must be sent
via a potential-free relay. The demand signal must be sent via 0–10 V.
The cooling unit has internal communication between the frequency inverter and
the expansion valve’s control equipment. Communication takes place through
the Modbus protocol.
Circuit board
The circuit board in the cooling unit is internally prewired and tested at the fac-
tory.
The circuit board contains:
Size 04:
Control centre with integrated expansion valve controller
Size 06-12:
• Compressor inverter
• Expansion valve controller
• Contactor
Size 16-21:
• Main switch
• Fuse
• Control unit
• Control unit for expansion valve