Carrier Pro-Dialog CONTROL 4 User Manual page 55

The lead pulldown time tells how long after starting the lead chiller (one time after the master chiller status has been
manually started) before checking whether to start an additional chiller. This time delay gives the lead chiller a
chance to pull down the loop temperature before starting another chiller.
If a communication failure is detected between the master and the slave then, all master/slave functions shall be
disabled and chillers shall return to standalone operations until communication is reestablished.
Note: to ensure that no compressor is started before the flow rate is correctly established then, the water flow control
is absolutely required on the lag chiller for master slave operations.
The figures below illustrate master/slave application for the most common plant layouts. Those figures are not
exhaustive.
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CARRIER SA
30GX&HX PRO_DIALOG 4 V.2
COOL_LWT
COOL_EWT
SLAVE PUMP
Typical parallel Master/slave chillers, dedicated primary pumping, variable flow
COOL_LWT
COOL_EWT
Typical parallel Master/slave chillers, common primary pumping, constant flow
NOT TO BE DISCLOSED TO PERSONS OUTSIDE CARRIER ORGANIZATION
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USER'S GUIDE FOR
CHWS temp sensors
COOL_LWT
COOL_EWT
MASTER PUMP
Leaving water control
CHWS temp sensors
COOL_LWT
COOL_EWT
COMMON PRIMARY PUMP
Leaving water control
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ARRIER S A
ECG-UG-02-002
Page: 54/98
Rev: Original
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