Control For Prevention Of Wrong Operation And Wrong Settings; Demand Control - Hitachi SAMURAI Series Service Manual

2. Control Functions
Control functions on the module

2.1.8 Control for prevention of wrong operation and wrong settings

In the following cases, an alarm is output as wrong operation.
1 Wrong activation of the operation controls
A wrong operation alarm is displayed when there is a remote input (including external thermo signal) while the unit
is stopped, regardless of "local/remote switch" being switched to local (local operation mode). Also, while on remote
operation mode, even if there is a local input (run switch on the control display part of the main unit) while the unit is
stopped, it is ignored and no alarm is displayed.
2 Wrong local/remote activation
When switching the operation mode from local to remote, or from remote to local, using the "local/remote switch" while
the chiller unit is in operation, the chiller unit is stopped and a wrong operation alarm is displayed.
3 Wrong setting of DIP switches
A wrong setting alarm (40-40) is displayed upon power ON in case that DIP switches are set to an impossible setting.

2.1.9 Demand control

It is a control that allows to cause a forced thermo OFF of the chiller unit with orders from the local control panel (by means
of peak cut, etc.) or to restrain the maximum limit of compressor operating capacity. Since it also allows to force a change
of the operation capacity, in response to the load of the facility, it is a convenient function to perform temperature control
from the local control panel.

Forced thermo OFF function
a. Contents of activation
When it is required to stop the compressor temporarily, output that order through the relay contact.
When this signal is received, the chiller unit forces the compressor to stop, and it becomes thermo OFF status.
(The operation of the cold water pump continues)
Also, when this order is released, the main unit returns to normal operation by thermo ON.
b. Time chart
RUN
STOP
Compressor
ON
External signal X
OFF
A
N O T E
In case of using the function to control the group (Master/Slave), forced thermo OFF order only applies to the
chiller units that have received it. When using this function, arrange the wiring to all the chiller units.
c. Wiring method
Arrange wiring as shown below.
20
SMGB0097 rev.0 - 07/2015
Automatic operation
depending on the thermo of
the main unit
Run control
Control board of the chiller unit
150 151 152 153 154
SW6
230V
Automatic operation
depending on the thermo of
Forced thermo OFF
the main unit
Forced thermo
Power source
OFF switch
of the local
control board
Stop control