GENER
AL INFORMA
TION
PR
ODUC
T INFORMA
TION
SY
STEM DESIGN
INTEGR
ATION INT
O SY
STEM
ORDERING INFORMA
TION
System evaluation
Single envelope control: Limit speed range from 2400 to 6000RPM
Manage operating envelope
VZH drive can only protect the compressor from
over current. To manage operating envelop, an
advanced envelope protection principle needs
to be used with variable speed compressors.
This solution offers much better protection than
basic protection, and also offers the possibility
to adjust running conditions to avoid tripping
(for example reduce compressor speed when
reaching high pressure limit).
The advanced protection principle is based
on a permanent measurement of suction
and discharge pressure. Unit controller is
permanently checking that the compressor is
running within the defined envelope.
When compressor reach a limit, controller can act
on different parameter to avoid unit tripping.
On top of suction and discharge pressure
limitations, the discharge T° must remain below
135°C (275°F).
Low pressure switch and high pressure switch
remain necessary as an ultimate protection.
The whole envelope can be used on the whole
speed range, see “Single application envelope”
Depending on speed range needed, two types of
controls to be considered
• Speed range limited from 2400RPM to 6000RPM
• Full speed range from 1000RPM to 6000RPM
Protection required
• HP switch*
• LP switch*
• DGT set @ 135°C (275°F) if necessary see “Discharge T°
protection”
• Measurements of suction and discharge pressure,
unit controller with is permanently maintaining
compressor within its envelope.
• drive setting:
parameter 4-11[ Motor speed low limit(rpm)]:
set value as 2400
HP switch setting
MOP
LP swit
ch setting
Condensing pressure control
DGT
4200-6000r
pm
2400-6000rpm
Minimum pr
essur
e
ratio
Controller do not need to manage speed
limitation according to operating conditions.
Operation is allowed in area 1.1; 1.2 ; 1.3.
SY
STEM DESIGN
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AB237586440343en-000601