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Air and Water cooled inverter chillers and heat pump
D-EOMZC00105-17EN
Operation Manual
48/84
EWAD TZ - EWAD TZ B -EWWD VZ
Air and Water cooled inverter chillers and
heat pump
5.2.8
High Condensing Pressure
When the circuit is running and the condensing pressure rises above the safety limits the circuit control logic
reacts at two different levels in order to recover the normal running conditions.
The two different levels, called High Pressure Hold and High Pressure Unload limits, are calculated by the
controller from the maximum condenser pressure allowed by the compressor envelope. This value depends
from evaporating pressure as reported in the figure below.
If the condensing pressure rises above the High Pressure Hold limit, compressor is inhibited to increase its
running capacity.
This condition is indicated on the controller display in the circuit status as “
Run: Cond Press
High”. The limit is calculated in terms of saturated condensing temperature; the status is automatically cleared
when the saturated condensing temperature rises above the High Pressure Hold limit by 5.6°C.
If the condensing pressure rises above the High Pressure Unload limit,
compressor is unloaded in order to
recover the normal operating conditions.
This condition is indicated on the controller display in the circuit status
as “
Run: Cond Press High”. The status is automatically cleared when the saturated condensing temperature
rises above the High Pressure Hold limit by 5.6°C.
See section 6.6.17 to troubleshoot this problem.
5.2.9
High Vfd Current
When the compressor is running and its output current rises above the safety limits the circuit control logic
reacts at two different levels in order to recover the normal running conditions. Safety limits are calculated by
the controller based on the selected compressor type.
If the running current rises above the Running Current Hold limit (101% of RLA), compressor is inhibited to
increase its running capacity.
This condition is indicated on the controller display in the circuit status as “
Run:
High VFD A
mps”.
If the condensing pressure rises above the Running Current Unload limit (105% of RLA),
compressor is
unloaded in order to recover the normal operating conditions.
This condition is indicated on the controller
display in the circuit status as “
Run: High VFD Amps
”. The status is automatically cleared when the running
amps falls below the hold limit.
5.2.10 High Discharge Temperature
When the compressor is running and its discharge temperature rises above
the safety limits the circuit control
logic reacts at two different levels in order to recover the normal running conditions.
If the discharge temperature rises above the Discharge Temperature Hold limit (95°C), compressor is inhibited
to increase its running capacity. This condition is indicated on the controller display in the circuit status as
“Run: High Discharge Temp
”.
If the discharge temperature rises above the Discharge Temperature Unload limit (100°C),
compressor is
unloaded in order to recover the normal operating conditions.
This condition is indicated on the controller
Safe Operation Area
Evap. Sat. Temp.
Cond. Sat.
Temp.
Hi Press Trip
Hi Press Hold
Hi Press Unload