Carel kVent, Руководство пользователя

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kVent – rel 3.1 – 22/06/2018
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Note: To disable external temperature compensation is
possible to setup minimum compensation equal to maximum
compensation.
Supply regulation 5.4.2
The temperature regulation is based on supply temperature
and its setpoint. If the setpoint set is the room set or return set,
according to configuration parameter (I008), this will be
converted to supply set.
To calculate the power of devices, a PID sequence is used.
The following graph show the PID sequence in case of cooling:
The following graph show the PID sequence in case of
heating:
With a unique setpoint and different sets of PID parameters,
the first request is calculated with a standard PID. The second
request starts when the first one has reached 100%. The
setpoint for the second device regulation is the same, while the
PID set of parameters are different. According to the PID
behaviour of the second device, the percentage of activation of
the second device at the start up should be equal to ‘’offset’’,
but thanks to the incremental PID it is possible to consider only
the last calculated delta so that there aren’t any bumps, then
the second device will start from the minimum output, then it
will regulate according to PID parameters and supply
temperature.
In case we have more devices and one is not available when
required from the sequential PID regulation - for activation
conditions not verified (i.e. recovery conditions) or active
alarms - the request passes to the other one. If the first device
becomes available again the device will be turned on at 100%.
5.5 Fresh air regulation
In case of unit without the mixing damper, the supply air is
always coming from the outside: if the external temperature is
better than the room or return temperature and the activation
of freecooling/freeheating is verified (external temperature
lower than the regulation temperature of a settable delta), the
bypass damper opens and the heat exchanger is bypassed.
In the following picture we represent the ‘’freecooling’’
enabling, that in case of unit without the mixing damper is the
by-pass damper activation condition, considering as example
the room temperature as regulation variable.
The freecooling is enabled if the external temperature is higher
than the lower supply temperature threshold, while the
freeheating is enabled if the external temperature is lower than
the upper supply temperature threshold.
The bypass damper can be modulated to reach the desired
temperature for the supply air temperature, because the
freecooling can be considered as the first step of sequential
PID regulation.
In
case of unit with the mixing damper, the
freecooling/freeheating conditions are the same, but mixing
damper and external one modulate accordingly, and the logic
acts on the bypass damper as in the previous case.
Night kick 5.5.1
If the unit is in standby mode, it starts at a certain hour (H016)
in the night to check the conditions and if there is requests, the
unit switch ON. When conditions are reached, the unit goes
back to standby.
5.6 Humidity regulation
The regulation of the unit could be done according to return,
supply or room set, according to configuration parameter
(I009). The regulation of humidity in kVent is done by absolute
humidity.
Absolute humidity setpoint is the conversion between the
actual temperature setpoint (room, return or supply) and the
relavtive humidity set that the user can change.
Absolute humidity is the conversion between the actual
temperature and the room relative humidity.
Based on these conversions, it’s possible to determine if the
unit should go in humidifying or dehumidifying mode. When the
humidity goes to change mode, a delay is provided to avoid
fast change of humidity control.
In case of regulation on return or room temperature, the
application check the supply humidity limits to avoid water of
the ducts. Closer the supply humidity is to the limits, lower the
humidity PID can act.
In case of regulation on supply, the humidity request goes
directly to the devices.
During dehumidification:
-
The signal to control the cooling devices is calculate from
the maximum between output temperature PID and the
output humidity PID.
- The main heating devices are disabled and the reheaters
works to compensate the cooling effect.
- Mixing damper is closed.
During humidification:
-
Mixing damper is open 100%.
5.7 Devices activation
ON/OFF Recovery 5.7.1
In case of ON/OFF recovery, kVent calculate modulating
recovery request anyway. The digital output is activated by
time, calculated by the request, with a fixed period of 10
minutes.
For example if the request is 60%, the digital output is ON for
360s and OFF for 240s, so the following graph show the
working logic.
Supply temp.
Set
Recovery
E011
E012
Cooling device
B008
B009
100%
0%
Mixing
E024
E025
Set
Recovery
E006
E007
Heating device
A016
A017
100%
0%
Reheat
A035
A036
Mixing
E022
E023
Supply temp.
Set
Room – Ext Temp.
Delta
2.0°C
Set
Dehumidification
Humidification
Delay
F013 Band
F014 Delay
F013