uca tech tips buckboosttransformers

8/10/2019 UCA Tech Tips BuckBoostTransformers

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United CoolAirmanufactures units that

can be applied with avariety of voltages. Some

applications utilize an

input or supply voltage of277-1-60. This power supply

comes from a 460-3-60(4-wire) system (The Neutral

Leg and the Line sideopposite the neutral leg).

While some componentsare available for direct

application of 277-1-60power, most manufacturers

(including United CoolAir)

nd that the use of abuck-boost transformer

to lower the voltage ismore cost effective. The

units are fabricated using

components suitablefor 208/230-1-60 power

supply. The control voltagetransformer is wired on the

230-volt tap to provide the24-volt control voltage.

Selecting a Buck-BoostTransformer

The following information

should be conrmed for

the application:

Line Voltage Conrmthat the supply / input

voltage is 277.

Frequency Input power

supply frequency mustmatch the equipment

either 50 or 60 Hertz (Hz).This TechTip is based on

only applications of 60

Hz.

Phase The supply / input powerphasing must be the same as

the equipment requirements.

The TechTip is based on single-phase applications.

Load KVA or Load Amps You

only need to know one or theother. This information usually

can be found on the unit

nameplate(s). On United CoolAirequipment the Minimum Circuit

Ampacity (MCA) should be used

as the Load Amps.

Selecting and ApplyingBuck-Boost Transformers

BUCK-BOOST TRANSFORMERS

The transformer is used to buck(decrease) the incoming power

supply from 277 volts down to the

230 volts required for the unit. Table1 lists the buck-boost transformers

available from United CoolAir.

Read down the column until yousee a KVA or Amp value that is just

higher than the equipment to be

operated.

Table 1 Available Buck-Boost Transformers

Single-Phase

UCA

Line Voltage 277

Part Number Model

(Available)

Load Voltage

(Output) 230

KVA 1.44

4CA1901 T-1-81064 Load

Amps 6.25

Max. Size of

Fuse or Breaker10

KVA 2.88

4CA1902 T-1-81065 Load

Amps 12.50

Max. Size of

Fuse or Breaker15

KVA 4.31

4CA1903 T-1-81066 Load

Amps 18.75

Max. Size of

Fuse or Breaker20

KVA 5.75

4CA1904 T-1-37920 Load

Amps 25.00

Max. Size of Fuse or Breaker 30

KVA 8.63

4CA1905 T-1-37921 Load

Amps 37.50

Max. Size of

Fuse or Breaker40

KVA 11.5

4CA1906 T-1-37922 Load

Amps 50.00

Max. Size of

Fuse or Breaker60

KVA 17.25

4CA1907(1) T-1-37923 Load

Amps 75.00

Max. Size of

Fuse or Breaker80

(1) Model contains lifting ears.


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Figure 1 Transformer Connection DiagramConnect the transformeraccording to the diagram to theright. Only one (1) transformer is

required in the wiring diagramfor each power supply to theequipment.

Notes:

1. The symbol O used inthis connection diagram

illustrates where to eldinstall an Overcurrent

protective device (typicallya fuse or circuit breaker)

when one input conductoris grounded and theother input conductor is

ungrounded.

2. When both input conductorsare ungrounded an

Overcurrent protectiondevice is required to be

installed in series with eachinput conductor.

3. For additional informationrefer to the National

Electrical Code, Article 450-4.

General

The installation, operationand maintenance of dry-type transformers should beperformed by an electrician or

other qualied personnel whoare familiar with international,national or local electricalcodes. Familiarity with thepotential shock hazardsassociated with electricalequipment is also necessary.

Encapsulated units are NEMA3R enclosures suitable for eitherindoor use in harsh environmentsor for outdoor use. CE markedunits have a protection index ofIP23.

The transformer must beinstalled per the NationalElectrical Code (NEC) and localcode requirements. CE markedtransformers must be installed

per EN 60742.

Inspection and Handling

The transformer should beinspected carefully upon receiptto check for any visible orconcealed damage that mayhave occurred during shipment.If damage is found, a claimshould be led immediately with

the carrier.

Transformers fty-ve (55)pounds or larger are providedwith lifting ears. Incorrecthandling can bend theenclosure, cause other damageor result in personal injury. (P/N4CA1907 contains lifting ears).

Installation

When installing a buck-boosttransformer, always follow allapplicable national and localcodes. Outside installation ofthe transformer should have thewiring in a conduit or as requiredby national and local codes.

Encapsulated transformers canbe installed indoors or outdoors.When installed outdoors, theseunits should be installed withthe wiring compartment downto prevent the entrance ofmoisture. Some encapsulated

units have a top-entry wiringcompartment and can beinstalled vertically (wiringcompartment up).

For indoor oor mounting ofan encapsulated unit thathas a bottom-entry wiringcompartment, the unit can beinstalled horizontally (on its backside) for ease of making wire

connections.

CAUTION: Do not makeconnections other than thoseshown. The transformer must

be as large (KVA) as the load itmust operate. Never exceed thenameplate rating as this could

result in overheating, reduced lifeexpectancy or worst cases, re.


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Electrical Connections

Refer to the transformernameplate label or enclosedwiring diagram for primaryand secondary voltagecombinations, frequencyand number of phases. Tapconnections and voltagecombinations are also listed on

the diagram or nameplate.

Proper assembly of the eldwiring to the transformer leadsis extremely important. Makecertain that the connector orterminal is sized for the cable.Space and insulate connectionsor terminals per the NEC.

Grounding

All dry-type transformers havea ground stud in the enclosure.The transformer enclosureshould be solidly groundedto protect personnel. Thecustomer-supplied groundingconductor should have acurrent-carrying capacity tomeet international, national and/ or local requirements.


Maintenance

Non-ventilated encapsulated

styles only require periodicwiping of dust and dirt from

the outside of the caseunder normal conditions

and environments. Adverseconditions may require morefrequent inspections.

If a dry-type transformeraccidentally gets wet, it must

be cleaned and thoroughlydried before energizing.

Otherwise, complete failurecould result.

Storage

Encapsulated transformers

should be stored in a clean,dry area. Care shoud be

taken to prevent moisture orcondensation from entering

the transformer. If storedoutside, the transformer mustbe covered and protected

from water, dust and otherairborne contaminants.

Hazardous Voltage.Will Cause SeverePersonal Injury or

Death.

Turn Power OffSupplying DeviceBefore Installing

WARNING: Danger of electricshock! Do not remove partsor make connections while

transformer is energized.

CAUTION: Never perform internalmaintenance while the unit is

energized!

NOTICE: These instructions are

general in nature and may notcover all variations in transformer

design or conditions of installation,operation and maintenance in

enough detail to meet customerneeds. Additional instructions maybe included with the transformer.If you need further information orshould a problem arise, please

contact the manufacturer.


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Notes


Form TT002 (0513)

BEA 1K (0513)

491 East Princess Street, York, PA 17403 Toll Free 1-877-905-1111 Phone (717) 843-4311 Fax (717) 854-4462e-mail: [email protected] www.unitedcoolair.com

2008 United CoolAir Corporation Manufacturer reserves the right to make changes without notice.

uca tech tips buckboosttransformers

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