Carrier 23XL Especificações descarregar pdf (Página 49)

Inspect Wiring

Do not apply any kind of test voltage if the machine is

under a dehydration vacuum. Insulation breakdown and

serious damage may result.

1. Examine wiring for conformance to job wiring dia-

grams and to all applicable electrical codes.

2. Connect voltmeter across the power wires to the com-

pressor starter and measure the voltage. Compare this

reading with the voltage rating on the compressor and

starter nameplates.

3. Compare the ampere rating on the starter nameplate with

the compressor nameplate. The overload trip amps must

be 108% to 120% of the rated load amps.

4. The starter for a screw compressor motor must contain

the components and terminals required for PIC refrig-

eration control. Check certiﬁed drawings.

5. Check the voltage to the pumpout compressor starter and

power panel and compare to the nameplate values.

6. Be sure that fused disconnects or circuit breakers have

been supplied for the power panel and pumpout unit.

7. Check that all electrical equipment and controls are prop-

erly grounded in accordance with job drawings, certi-

ﬁed drawings, and all applicable electrical codes.

8. Make sure that the customer’s contractor has veriﬁed

proper operation of the pumps, cooling tower fans, and

associated auxiliary equipment. This includes ensuring

that motors are properly lubricated and have proper elec-

trical supply and proper rotation.

9. For ﬁeld-installed starters only, test the machine com-

pressor motor and its power lead insulation resistance

with a 500-v insulation tester such as a megohmmeter.

Factory-mounted starters do not require a megohm test.

a. Open the starter main disconnect switch and follow

lockout/tagout rules.

If the motor starter is a solid-state starter, the mo-

tor leads must be disconnected from the starter be-

fore an insulation test is performed. The voltage

generated from the tester can damage the starter’s

solid-state components.

b. With the tester connected to the motor leads, take 10-

second and 60-second megohm readings as

follows:

6-Lead Motor — Tie all 6 leads together and test be-

tween the lead group and ground. Next tie leads in

pairs, 1 and 4, 2 and 5, and 3 and 6. Test between

each pair while grounding the third pair.

3-Lead Motor — Tie terminals 1, 2, and 3 together

and test between the group and ground.

c. Divide the 60-second resistance reading by the

10-second reading. The ratio, or polarization index,

must be one or higher. Both the 10- and 60-second

readings must be at least 50 megohms.

If the readings on a ﬁeld-installed starter are unsat-

isfactory, repeat the test at the motor with the power

leads disconnected. Satisfactory readings in this sec-

ond test indicate the fault is in the power leads.

NOTE: Unit-mounted starters do not have to be meg-

ohm tested.

10. Tighten up all wiring connections to the plugs on the

SMM, 8-input, and PSIO modules.

11. Ensure that the voltage selector switch inside the power

panel is switched to the incoming voltage rating.

12. On machines with free-standing starters, inspect the power

panel to ensure that the contractor has fed the wires into

the bottom of the panel. Wiring into the top of the panel

can cause debris to fall into the contactors. Clean and

inspect the contactors if this has occurred.

Carrier Comfort Network Interface — The Carrier

Comfort Network (CCN) communication bus wiring is sup-

plied and installed by the electrical contractor. It consists of

shielded, 3-conductor cable with drain wire.

The system elements are connected to the communication

bus in a daisy chain arrangement. The positive pin of each

system element communication connector must be wired to

the positive pins of the system element on either side of it;

the negative pins must be wired to the negative pins; the sig-

nal ground pins must be wired to signal ground pins.

To attach the CCN communication bus wiring, refer to

the certiﬁed prints and wiring diagrams. The wire is inserted

into the CCN communications plug (COMM1) on the PSIO

module. This plug also is referred to as J5.

NOTE: Conductors and drain wire must be 20 AWG (Ameri-

can Wire Gage) minimum stranded, tinned copper. Indi-

vidual conductors must be insulated with PVC, PVC/nylon,

vinyl, Teﬂon, or polyethylene. An aluminum/polyester 100%

foil shield and an outer jacket of PVC, PVC/nylon, chrome

vinyl or Teﬂon with a minimum operating temperature range

of −20 C to 60 C is required. See table below for cables that

meet the requirements.

MANUFACTURER CABLE NO.

Alpha 2413 or 5463

American A22503

Belden 8772

Columbia 02525

When connecting the CCN communication bus to a sys-

tem element, a color code system for the entire network is

recommended to simplify installation and checkout. The fol-

lowing color code is recommended:

SIGNAL CCN BUS CONDUCTOR PSIO MODULE

TYPE INSULATION COLOR COMM 1 PLUG (J5) PIN NO.

+ RED 1

Ground WHITE 2

- BLACK 3

Check Starter

BE AWARE that certain automatic start arrangements

can engage the starter. Open the disconnect ahead of

the starter in addition to shutting off the machine or pump.

Use the instruction and service manual supplied by the

starter manufacturer to verify that the starter has been in-

stalled correctly.

The main disconnect on the starter front panel may not

deenergize all internal circuits. Open all internal and re-

mote disconnects before servicing the starter.

When a starter safety trip device activates, wait at least 30

seconds before resetting the safety. The microprocessor main-

tains its output to the 1CR relay for 10 seconds to determine

the fault mode of failure.

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Carrier 23XL Especificações Página 49

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