Carrier 30GX - Description of the INPUT Menu

21
Sample D T reset configuration:
In this example, the cooling setpoint starts
to be reset with effect from a D T at the
evaporator of 5.0°C (full load) up to a
maximum reset of 3°C at a D T of 3.0°C.
This example assumes that the:
• Reset based on D T has already been
configured in the configuration menu (see
section 4.2.10, configuration).
The configuration shall be as follows:
• Zero reset if the evaporator D T (i.e. D T for
zero reset - Item 10) is greater than 5.0°C;
• Maximum reset 3°C (Maximum reset
value - Item 12) if the evaporator D T (i.e.
D T for maximum reset - Item 11) is lower
than 3.0°C.
The setpoint curve is then as follows:
Cooling setpoint D T reset
MAXIMUM RESET VALUE
BUILDING LOAD
D T FOR ZERO RESET
D T FOR MAXIMUM RESET
RESET VALUE
% BUILDING LOAD
D T RESET REFERENCE VALUE
However, the reset parameters remain
accessible to any type of configuration
and make it possible to obtain any
combination of slope and reset origin in
response to fluctuations in the value of
D T on the active heat exchanger.
Reset based on D T is a linear function
which requires three parameters to be
configured:
• A reference D T at which the reset is
zero: this is the D T for zero reset
referred to in item 10 for cooling mode
or item 15 for heating mode.
• A reference D T at which the reset is at
maximum: this is the D T for maximum
reset referred to in item 11 for cooling
mode or item 16 for heating mode.
• The maximum reset value: this is the
maximum reset value referred to in item
12 for cooling mode - item 17 for
heating mode.
Range: D T for zero reset:
0 to 13.8°C
D T for maximum reset:
0 to 13.8°C
Maximum reset value:
-16.6 to 16.6°C
The reset is calculated as follows if the
value of the D T for zero reset exceeds the
value of the D T for maximum reset
(negative slope):
• The reset is zero if the current D T
exceeds the reference value D T for zero
reset.
• The reset equals the maximum reset
value if the current D T is lower than the
reference value D T for maximum reset.
• If the current D T is between the
reference values D T for zero reset and
D T for maximum reset, the reset value
is calculated by linear interpolation
between the maximum reset value and
0.
The reset is calculated as follows if the
value of the D T for zero reset is lower
than the value of the D T for maximum
reset (positive slope):
• The reset is zero if the current D T is
lower than the reference value D T for
zero reset.
• The reset equals the maximum reset
value if the current D T exceeds the
reference value D T for maximum reset.
• If the current D T is between the
reference values D T for zero reset and
D T for maximum reset, the reset value
is calculated by linear interpolation
between 0 and the maximum reset
value.
4.2.8 - Description of the INPUT menu
This menu displays the status of the controller inputs. Access
to this menu is read-only.
ITEM FORMAT DESCRIPTION
0 open/close Remote start/stop contact status
1 open/close Remote cooling setpoint selection contact status
2* open/close Remote heat/cool selection contact status
3* open/close Remote reclaim mode selection contact status
4 open/close Demand limit contact status
5 open/close Evaporator water flow control contact status
6 open/close Condenser water flow control contact status
7 open/close Oil level control contact status circuit A
8 open/close Oil level control contact status circuit B
9 nn Heat reclaim condenser water flow control contact status
10 nn Drain pressostat contact status, circuit A
11 nn Drain pressostat contact status, circuit B
12 nn Evaporator liquid refrigerant level circuit A
13 nn Evaporator liquid refrigerant level circuit B
14 nnn 0-10 V d.c signal
Key:
* : This item is displayed in certain unit configurations only.