1088917-YIM-B-1014
Johnson Controls Unitary Products 37
Once the appropriate relay and capacitor are obtained, install
the capacitor across LR terminals '3' & '4' and make the
following wiring connections:
• LR '1' to BAS controller
• LR '2' to BAS controller
• LR '3' to UCB 'X'
• LR '4' to UCB 'C'
'VFD-Ready' For Customer-installation
Units configured as 'VFD-ready' provide provisions for a
customer-installed drive. The physical dimensions of VFDs can
vary greatly among manufacturers, horsepower ratings and
voltage requirements. Keep in mind that drive manufacturers
also require various minimum clearances to allow for adequate
internal cooling of the drive during operation.
The unit comes with a mounting bracket installed in the Blower
Access compartment which may accommodate other vendor's
drives depending on their size. In order to utilize the unit's
mounting bracket, the maximum recommended drive
dimensions are as follows:
For 5-hp motor applications........................ 13" H x 6" W x 7" D
For 7.5 thru 15-hp motor applications ........ 13" H x 8" W x 8" D
If the drive will not fit in the allotted space, then it will need to be
mounted elsewhere; either within the building on a perpendicular
wall which is not subjected to excessive temperature, vibration,
humidity, dust, corrosive gas, explosive gas, etc., or within an
appropriate enclosure rated for outside installation to safeguard
against moisture, dust and excessive heat.
The power leads to the drive (L1, L2, L3) and from the motor
(T1, T2, T3) along with the respective ground wires are supplied
with the unit and need to be connected after the drive is
installed.
A terminal block located in the control box is provided for field
connection of the VFD speed reference signal (2-10 VDC) and
to the normally-open, run-permit auxiliary contact. The use of
shielded cable is recommended for the above control wiring
connections.
For VFD-ready units also equipped with gas/electric heat, a
terminal block located in the unit's control box and connected to
the VAV board's "VAV BOX" terminal, must be field wired to the
building's VAV boxes to ensure fully open dampers during
heating operation.
Optional Hot Gas Bypass (HGBP)
To allow for low cooling load operation, a direct-acting,
pressure-modulating bypass control valve installed on the
system #1 discharge line is used to divert high temperature,
high pressure refrigerant around the TXV in order to maintain a
desired minimum evaporator pressure.
The opening pressure of the bypass valve is fully adjustable
between 95 and 115 psig with a factory-setting of 105 psig.
HGBP is standard on all units with VAV and optional with CV
units.
Do not connect AC power to the T1, T2, T3 drive
terminals to prevent damage to the VFD.
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