Power Supply Wiring; 115vac Control Supply Transformer; Control Wiring; Volts Free Contacts - Quantech QTC4 STYLE A Series Installation Operation & Maintenance

Air-cooled screw liquid chillers with variable speed drive, 150 - 500 tons, 525 - 1750 kw, 2 compressor, 60 hz.

SECTION 4 - INSTALLATION

Copper power wiring only should be used for supply-

ing power to the chiller. This is recommended to avoid

safety and reliability issues resulting from connection

failure at the power connections to the chiller. Alumi-

num wiring is not recommended due to thermal char-

acteristics that may cause loose terminations result-

ing 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 chiller, 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 chiller.

Caulk power and control wiring conduit

entering the power panel to assure moist

air from the building cannot enter the

panel.

POWER SUPPLY WIRING

Units require only one 3-phase supply, plus earth.

Connect the 3-phase supplies to the circuit breaker

located in the panel (See Table 4 on Page 47).

Connect a suitably sized earth wire to the PE terminal

in the panel.

115VAC CONTROL SUPPLY TRANSFORMER

A 3-wire high voltage to 115VAC supply transformer

is standard in the chiller. This transformer is mounted

in the cabinet and steps down the high voltage supply

to 115VAC to be used by the Controls, VSD, Feed and

Drain Valve Controller, Valves, Solenoids, Heaters, etc.

The high voltage for the transformer primary is

taken from the chiller input. Fusing is provided for the

transformer.

Removing high voltage power to the

chiller will remove the 115VAC supply

voltage to the control panel circuitry

and the evaporator heater mat. In sub-

freezing weather, this could cause serious

damage to the chiller due to evaporator

freeze-up. Do not remove power unless

alternate means are taken to ensure op-

eration of the control panel, evaporator

heater mat, and waterbox heaters.

CONTROL WIRING

All control wiring utilizing contact closures to the con-

trol panel terminal block is nominal 115VAC and must

be run in shielded cable, with the shield grounded at

the panel end only, and run in water tight conduit. Run

shielded cable separately from mains cable to avoid

electrical noise pick-up. Use the control panel cable

entry to avoid the power cables.

Voltage free contacts connected to the panel must be

suitable for 115VAC10 ma (gold contacts recommend-

ed). 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. The above precautions must

be taken to avoid electrical noise, which could cause a

malfunction or damage to the unit and its controls.

VOLTS FREE CONTACTS

Chilled Liquid Pump Starter

Terminals 23 and 24 on 1TB close to start the chilled

liquid pump. This contact can be used as a master start/

stop for the pump in conjunction with the daily start/

stop schedule. Cycle the pumps from the unit panel if

the unit will be operational or shut-down during sub-

freezing conditions. Refer to the Evaporator Pump

Control on Page 96 for more information on testing

the pumps.

Run Contact

Terminals 21 and 22 on 1TB close to indicate that a

system is running.

Alarm Contacts

Each system has a single voltage-free contact, which

will operate to signal an alarm condition whenever any

system locks out, or there is a power failure. To obtain

system alarm signal, connect the alarm circuit to volt

free Terminals 25 & 26 (Sys 1), Terminals 27 and 28

(Sys 2) of 1TB.

SYSTEM INPUTS

Flow Switch

A chilled liquid flow switch of suitable type MUST be

connected between Terminals 2 and 13 of 1TB to pro-

vide protection against loss of liquid flow, which will

cause evaporator freeze-up if the chiller is permitted

to run. The flow switch circuitry is a 115VAC circuit.

Contacts must be rated for low current (5mA). Gold

contacts should be used.

FORM QTC4-NM1

ISSUE DATE: 4/2/2018

QUANTECH

Table of Contents

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