evaporator.
6. Stop valves must be installed at the inlet of each unit to balance chilled liquid distribution.
7. A minimum interval must be reserved for field wiring, commissioning and maintenance.
8. Refer to single unit drawings for detailed dimensions.
WIRING
The units are shipped with all factory-mounted controls wired for operation.
Field Wiring
– Power wiring must be provided through a protector device (fused disconnect switch or
circuit breaker) to the input unit terminals in accordance with local code requirements. Maximum
current is given in Electrical Data.
Copper power wiring only should be used for supplying power to the unit. This is recommended to
avoid safety and reliability issues resulting from connection failure at the power connections to the
unit. Aluminum wiring is not recommended due to thermal characteristics that may cause loose
terminations resulting from the contraction and expansion of the wiring.
Aluminum oxide may also build up at the termination causing hot spots and eventual failure. If
aluminum wiring is used to supply power to the unit, AL-CU compression fittings should be used to
transition from aluminum to copper. This transition should be done in an external box separate to the
power panel.
Copper conductors can then be run from the box to the unit.
See unit wiring diagrams for field and power wiring connections, communication wiring connections,
modular wiring, alarm contacts, remote start/stop input, remote cooling/ heating switch, etc. Refer to
UNIT OPERATION for a detailed description of operation concerning aforementioned contacts and
inputs.
Pump Start Contacts
Terminal block XTB2
– terminals 21 to 22, are normally open contacts that can be used to switch field
supplied power to provide a start signal to the pump contactor. User-provided pump contactor and
thermal relay are required if the pump is field installed. The contacts will be closed when any of the
following conditions occur:
1. Any compressor is running
2. The unit(s) is on and no flow fault occurred
3. Anti-freezing operation
4. Pump circulation mode
The pump will not run if the micro panel has been powered up for less than 30 seconds, or if the pump
has run in the last 30 seconds, to prevent pump motor overheating. Refer to unit wiring diagram.
Alarm Status Contacts
Normally-open contacts are available for each unit. These normally-open contacts remain open when
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