INNOV@-pCO1-IOM-0907-E
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9.5 Automatic start and stand-by units
The boards connected with LAN network may be managed directly by the program under
“critical situations”,
that is in case of failure (alarms, black-out
…) or due to “Rotation” and
“Forcing” functions.
The program acts based on some parameters that can be displayed and modified on the board with LAN
address 1:
Boards mode operation: Not present, Present/No Rotation, Present/Rotation. These are 8
parameters, one for each board. Not present: unit not connected. Present/No Rotation: unit
physically connected with LAN network but not involved in the rotation function (however, unit can
manage the shared display, printing and Master Control function). Present/Rotation: unit involved in
Rotation too.
Number of units in stand-by mode: this parameter establishes the number of units, among the ones
selected in Present/Rotation mode, that must be set to stand-by mode (turned off, waiting for
enabling) when starting the unit by button. The parameter is automatically included between 0 and
the total number of Present/Rotation units minus one, to ensure start-up of at least one unit.
IMPORTANT
. The following functions cannot be executed if:
at least two units selected in Present/controlled mode are not present
the stand-by units set number is 0
The board with LAN address 1 provides for functions management; if the board is disconnected from LAN
network or it shuts down due to a black-out, the stand-by boards enable and the functions will be suspended
until unit 1 is reset. On the contrary, unit 1 stop by On-off or remote On-off button does not interrupt network
functions execution.
9.5.1 Critical situations
Units in Present/Rotation and stand-by modes are enabled in any of the following critical situations
concerning the running boards:
one of the boards has power cut off (black-out).
one of the boards signals a Serious alarm that enables alarm relay no. 8 (each alarm can be
programmed as serious or non-serious).
one of the boards disconnects from LAN network due to Rs485 line disconnection.
one of the boards is shut down by button or remote On-off digital input.
one of the boards is shut down due to a serious alarm (refer to alarms table).
In case a running unit is involved in any of the listed situations, a stand-by board is automatically enabled to
reset the number of running units. If, for example, two running units break or disconnect, the program
enables two stand-by units; when one of the units under critical situation resets, it is started again and the
spare unit returns to stand-by mode. If a critical situation involves the stand-by units, no LAN action occurs,
with the exception of alarm signalling on the involved unit.
9.5.2 Forcing
Units in Present/Rotation and stand-by modes are enabled automatically in case a running unit does not
reach the temperature set point for a certain time interval due to an excessive thermal load. Each unit
running in such a situation can require enabling of a stand-by unit. The parameters to be set for forcing are
Differential, Offset and Delay time, different for heating and cooling. The following diagram shows the forcing
function:
Forcing delay in Forcing delay in
heating mode cooling mode
Temperature set
HEATING COOLING
Ambient
12.0 16.0 20.0 23.0 26.0 30.0 34.0
temp.(°C)
4°C 3°C 3°C 4°C
Warm forc. offset Warm band Cold band Cold forc. offset
8°C 8°C
Warm forcing differential Cold forcing differential