McQuay Magnitude C Vintage, Инструкция по установке, эксплуатации и обслуживанию

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www.DaikinApplied.com 61 IOM 1210-1 • MAGNITUDE
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MODEL WMC CHILLERS
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Definitions
Active Amp Limit
Active amp limit is the actual amp limit imposed by an outside
signal such as the load limit function.
Active Capacity Limit
The active capacity setpoint is the setting in effect at any
given moment. Any one of several external inputs can limit a
compressor’s capacity below its maximum value.
Active Setpoint
The active setpoint is the parameter setting in effect at any
given moment. This variation can occur on setpoints that can
be altered during normal operation. Resetting the chilled water
leaving temperature setpoint by one of several methods such
as return water temperature is an example.
Condenser Recirc (Recirculation) Timer
A timing function, with a 30-second default after start, that
holds off tower fan control for the duration of the timing setting.
Dead Band
The dead band is a set of values associated with a setpoint
such that a change in the variable occurring within the dead
band causes no action from the controller. For example, if a
temperature setpoint is 44°F and it has a dead band of ± 2.0°F,
nothing will happen until the measured temperature is less than
42°F or more than 46°F.
Demand
Signal between 0 & 1000 sent from the compressor controller
to the compressor. This directs where the compressor needs to
be with capacity: increasing, stable, or decreasing.
Discharge Superheat
Discharge superheat is calculated using the following equation:
Discharge Superheat = Discharge Temperature – Condenser
Saturated Temperature
ELWT
Evaporator leaving water temperature. The “water” is any fluid
used in the chiller circuit.
ELWT Error
Error in the controller context is the difference between the
value of a variable and the setpoint. For example, if the ELWT
setpoint is 44°F and the actual temperature of the water at a
given moment is 46°F, the ELWT error is +2 degrees.
ELWT Slope
The ELWT slope is an indication of the trend of the chilled
water temperature. It is calculated by taking readings of the
temperature every few seconds and subtracting them from the
previous value over a rolling one-minute interval.
Error
In the context of this manual, “Error” is the difference between
the actual value of a variable and the target setting or setpoint.
Evaporator/Condenser Approach
The evaporator/condenser approach is calculated for each
circuit. The equation is as follows:
Approach = LWT – Saturated Temperature
Evap Hold-loading
This is a setpoint that establishes the minimum evaporator
pressure to which the chiller is allowed to go. It signals that the
unit is at full load so the no further loading will occur that would
lower the pressure even further.
Evap Recirc (Evaporation Recirculation)
Timer
A timing function, with a 30-second default, that holds off any
reading of chilled water for the duration of the timing setting.
This delay allows the chilled water sensors to take a more
accurate reading of the chilled water temperature.
EXV
Electronic expansion valve, used to control the flow of
refrigerant to the evaporator, controlled by the circuit
microprocessor.
Lenient Flow Logic
This option affords the chiller the maximum tolerance to
intermittent water flow loss detection, and reduces nuisance
chiller trips. Momentary loss of flow detection can be a result
of valve changes in the primary loop, as when staging another
chiller, or sudden changes in water temperature around the
flow sensor. Variable speed pumps operating at minimum flow
rates can exacerbate these flow issues.
Enabled, this logic detects a loss of flow signal (>5 Sec)
in either the condenser or evaporator and sets an internal
logic flag. Chiller operation is allowed to continue as long
as the vessel pressures and surge detection remain valid. If
condenser flow is lost and the pressure rises to within 5psi of
the condenser pressure trip point the chiller will shut down on
condenser flow loss alarm. If evaporator flow is lost and the
evap pressure drops to the EP-Unload set point the chiller will
shut down on evaporator flow loss alarm. If either flow signal is
lost and the surge logic is tripped, the chiller will shut down and
generate a flow loss alarm for whichever flow was missing.
The default setting for Lenient Flow logic in the WMC code is
On. Turning it off converts the flow loss alarms, to timer based.
Evap flow loss is adjustable from 12 down to 3s (default 12s),