York ZR240 Specifications download pdf (Page 29)

275864-YIM-C-0910

Johnson Controls Unitary Products 29

BAS-Ready VFD

Factory-installed VFD is also available with 'BAS-ready'

models. Terminal blocks are provided in the control box (in

place of the VAV control board) for field wiring of a customer-

installed BAS to receive 24 VAC power and to connect to the

following control signals:

• a duct static pressure transducer input signal (0-5 VDC)

• an economizer actuator input signal (2-10 VDC)

• an economizer actuator output signal (2-10 VDC)

• a VFD speed reference output signal (2-10 VDC)

The use of shielded cable is recommended for the above

control wiring connections.

NOTE: Factory-installed VFD is not available with factory-

installed BAS options due to space limitations in the

control box.

A solid-state, lock-out relay (LR) and 100-F, 50 VDC capacitor

must be field-supplied and installed to provide a means to

transmit a potential fault signal back to the BAS controller. The

specific relay part number required will depend upon the need

for either AC-output or DC-output. See price pages for further

details.

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 con

nected 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 0 and 80 psig with a factory-setting of 60 psig. HGBP

is standard on all units with VAV and optional with CV units.

If the unit is operated with the manual bypass switch in

the LINE (BYPASS) position and there are VAV boxes

present in the duct system, then boxes must be driven to

the full-open position using a customer-supplied power

source to prevent over-pressurizing and possible

damage to the ductwork.

Before beginning any service, disconnect all power to

the drive. Be aware that high voltages are present in the

drive even after power has been disconnected.

Capacitors within the drive must be allowed to discharge

before beginning service.

Do not connect AC power to the T1, T2, T3 drive

terminals to prevent damage to the VFD.

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York ZR240 Specifications Page 29

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