Technical data
4.20 Control Connections
Customer voltage free contacts must be
suitable for device contact rating to be 5 mA at
115 Vac. If the voltage free contacts form part
of a relay or contactor, the coil of the device
MUST be suppressed using a standard R/C
suppressor to avoid electrical noise which
could cause a malfunction or damage to the
unit.
To avoid the possibility of motor failure due to
excessive start cycles, the unit should not
normally be cycled using the remote
connections. Cycling of the unit based on
cooling demand is accomplished
automatically by the control panel. In addition,
the control panel has a programmable time
clock function as a standard feature with
holiday capability. This offers one preset
automatic Start-Stop per day on a seven day
calendar basis with the ability to program a
single additional holiday start and stop time up
to a week in advance.
4.20.1 Remote Start / Stop
(Start - TB4 terminals 1 & 7)
(Stop - TB4 terminals 1 & 8)
When the control panel is in the 'REMOTE' operating
mode, the 'COMPRESSOR' switch is in the 'RUN'
position and the 'REMOTE READY TO START
CONTACTS' (TB2: terminals 26 & 27) indicate the unit is
ready to start. Holding contacts open across the
'REMOTE STOP' connections and closing contacts
across the 'REMOTE START' connections' will start the
unit. A subsequent closure of the 'REMOTE STOP'
contacts causes the unit to shutdown.
If the 'REMOTE START' and 'REMOTE STOP'
connections are to be used at a remote control station
rather than by an EMS/BAS it is recommended that a
change over contact is used between the terminals.
When the unit is operated in 'REMOTE' mode using the
'REMOTE START-STOP' connections, an
'EMERGENCY STOP' by an operator or others will
'STOP' the compressor from the control panel and
prevent the unit from restarting. However, the operator
cannot locally start the compressor using the
'COMPRESSOR' start switch, when the control panel is
in the 'REMOTE' operating mode.
4.20.2 Remote / Local Cycling
(TB4 terminals 1 & 13)
The closure of an automatic reset device across these
terminals will permit the unit to operate in all operating
modes. Conversely, an opening of the device contacts
will inhibit the unit from operating.
4.20.3 Chilled Liquid Flow Interlock
(TB4 terminals 1 & 12)
A suitable flow switch which closes on presence of flow
must be installed between these contacts, to give
adequate protection against loss of chilled liquid flow.
4.20.4 Cooling Liquid Flow Interlock (Optional)
(TB4 terminals 1 & 11)
A suitable flow switch which closes on presence of flow
can be installed between these contacts, to provide
protection against loss of cooling liquid flow.
4.20.5 Multi Unit Sequence
(TB4 terminals 1 & 9)
For multiple unit installation applications, 'MULTI UNIT
SEQUENCE' connections are available to start and stop
each unit. The maintained closure of remote contacts
will permit the unit to operate in all operating modes with
the 'COMPRESSOR' switch in the 'RUN' position.
Conversely, an opening of the contacts will inhibit the
unit from operating.
4.20.6 Auxiliary Safety Shutdown
(TB4 terminals 1 & 31)
Momentary or maintained closure of a normally open
switch or relay contacts will cause the unit to shutdown.
The unit will not restart until the contacts open and a
manual reset and restart of the unit is carried out.
4.20.7 Remote Leaving Chilled Water Temperature
Setpoint Reset - PWM (TB4 terminals.1 & 19)
The locally programmed leaving chilled water
temperature setpoint can be reset bya1to11second
timed closure of remote contacts connected to these
terminals. The signal will only be accepted when the
control panel is in the digital 'REMOTE' operating mode.
An accepted signal will adjust the leaving chilled water
temperature up to 22.2°C upwards from the locally
programmed value. Unit capacity will be adjusted to
achieve the new setting of leaving chilled water
temperature, providing the compressor motor current is
below the current limit setpoint.
A one-second pulse corresponds to no offset and
therefore no adjustment of the preprogrammed leaving
chilled liquid temperature setpoint. An eleven second
pulse corresponds to the locally preprogrammed
maximum allowable offset (5.6°C, 11.1°C, 16.7°C or
22.2°C) above the leaving chilled water temperature
setpoint. The amount of offset varies linearly with
pulse-width.
160.81-ICOM-GB0 (01/02) 4-7