McQuay PFS 155C, Руководство по эксплуатации и обслуживанию

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OM 135 PFS 155C - 315C 33
Return - This measures the evaporator return water temperature and as the return comes back cooler (indicating cooling
load is reduced) the leaving water temperature is increased. This reduces motor amps and provides an operational cost
savings.
4-2OmA - This is an optional input to the MicroTech. This input is usually from a building automation system.
As the input changes from 4 to 20 mA, the leaving chilled water temperature is increased from local spt (in a linear
manner) until the max Lvg spt is reached. When the spt source is set to network, the 4-20 mA input is supplied to the
master MicroTech control. The master will issue reset instructions to the slave MicroTech. Upon network
communication failure the slave unit will revert back to local spt control. Network failure on a dual machine will require
immediate attention.
Oat - The leaving water temperature setpoint is increased as the outside air temperature decreases. The leaving water
temperature setpoint will be reset upward from the local spt to the max Ivg spt (in a linear manner) between the max reset
and no reset values. The outside air temperature can be used to determine when the building load will decrease because
of cooler outside air temperatures. Since the building load is reduced the leaving evaporator water temperature can be
increased providing reduced operational costs.
Ice - This option allows the chiller to operate at temperatures that are required by ice banks. Ice option requires an
external 24 Vac input to change the chiller from regular operation to ice operation. The local spt should be set to equal
the ice temperature plus the shutdn dt. The max Lvg spt would determine the normal or day operating temperature. All
refrigerant setpoints must be adjusted according to the operating temperatures and pressures.
Return Spt= This value will control the MicroTech if the chw reset option was set to return. When the return water
temperature reaches return spt the leaving evaporator water temperature will be increased to maintain the return spt.
The leaving water temperature will not exceed the max Lvg spt.
Reset Signal= The actual value of the external reset signal.
Max Reset At - A value must be entered if oat was selected as the chw reset option. Select an outside air temperature at
which the maximum reset will occur.
Menu 9, Stage Limiting
Press the "NEXT MENU" key and Menu 9 will be displayed. Menu 9 has two screens. This menu is password
protected and requires the operator password.
Item
Screen Line Display Field Range
1 Demand Limiting = xxx 1 No
Yes
1 Demand Limit = x Stgs 2
2 Dmd Signal = x mA 1
Network Limit = x % 2
3 Pulldn Rate= x° /m 1
1 Soft Load = xx 1
2 SoftLoad Max Stg = x 2
2 SoftLoad Remain Time = x Min 1
3 SoftLoad Max Timer = xx min 1
Demand Limit - Allows the MicroTech to control chiller motor amperage based on a remote 4-20 mA signal supplied by
a building automation system input. The 4-20 mA signal limits the capacity of the chiller and saves electrical demand
charges.
Menu 10, Set Time/Date
Item
Screen Line Display Field Range
1 1 Time Day Month and Year 1