Emerson ZR16-29KC, ZR16-24K4, ZR16-34KA, ZR38-54KA, ZR18-48K3 Application Engineering Bulletin

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Application Guidelines for 1.5 to 6.75 Ton Refrigerant

R-22, 407C, 134A Copeland Scroll

Introduction

The ZR*KA, ZR*KC, ZR*K3, & ZR*K4 Copeland Scroll® compressors include a wide range of capacities, electrical options, and features. Typical model numbers are ZR24K4-PFV and ZR81KC-TF5. This bulletin describes the operating characteristics, design features, and application requirements for these models. For additional information, please refer to the online product information accessible from the Emerson Climate Technologies website at www.emersonclimate. com. Operating principles of the Copeland Scroll are described in Figure 7 at the end of this bulletin.

The ZR*KA scroll compressors are designed for air conditioning systems only in the 12+ SEER range but may be applied to 10 SEER A/C systems if desired. They range in size from 16,000 to 54000 Btu/hr (4.7 to

15.8 kw-hr).

The ZR*K3 and K4 are models designed for 11+ SEER A/C and heat pump usage ranging in size from 16,000 to 61,000 Btu/hr (4.7 to 17.9 kw-hr).

The ZR*KC models are designed for 10 SEER A/C and heat pump usage ranging in size from 16,000 to 81,000 Btu/hr (4.7 to 23.7 kw-hr).

The models include a number of features outlined in the matrix below:

January, 2005

Reformatted November 2010

Compressors

IPR Valve-Internal Pressure Relief Valve

The internal pressure relief valve is located between the high side and the low side of the compressor. It is designed to open when the discharge to suction differential pressure exceeds 375 to 450 psid (26 – 32 kg/cm2). When the valve opens, hot discharge gas is routed back into the area of the motor protector to cause a trip.During developmental blocked fan testing, it is sometimes noted that the valve opens, but the compressor does not shut off while the discharge pressure continues to climb. This condition is normally

caused by refrigerant ood back and may be corrected

by using a more restrictive expansion device or reducing the refrigerant charge.

Internal Temperature Protection

The Therm-O-Disc snap disc device located between the high and low pressure side of the scroll. It is designed to open and route excessively hot discharge gas back to the motor protector. During a situation such as loss of charge, the compressor will be protected for some time while it trips on the protector. However, as refrigerant leaks

out, the mass ow and the amperage draw are reduced

and the scrolls will start to overheat. Normally, during air conditioning operation the problem is detected because of rising indoor temperatures before damage is done. This may not be the case during heat pump

or TOD is a temperature-sensitive

Motor

Frame Size*

ZR16-29KC 53 X X NO X X X X

ZR16-24K4 53 X X NO X X X X ZR16-34KA 53 X NO X X X X X ZR38-54KA 63 X NO X X X X X

ZR18-48K3 63 X X X X X X X ZR26-48KC 63 X X X X X X X

ZR54-61K3 70 X X X X X X X ZR54-81KC 70 X X X X X X X

* Approximate Shell Diameter (e.g. 53 = 5.5 Inches)

Application

AC HP

IPR TOD

Quiet Shut

Down

Discharge

Check Valve

Motor

Protector

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operation since backup heat will make up the decit. A

low pressure control is recommended for loss of charge protection in heat pumps for the highest level of system protection. A cut out setting no lower than 25 psig (2 kg/cm2) for air conditioning and 7 psig (0.5 kg/cm2) for heat pumps is recommended. The low pressure cut-out, if installed in the suction line to the compressor, can provide additional protection against a TXV failed in the closed position, outdoor fan failure in heating, a closed liquid line or suction line service valve, or a blocked liquid

line screen, lter, orice, or TXV. All of these can starve

the compressor for refrigerant and result in compressor failure. The low pressure cut-out should have a manual reset feature for the highest level of system protection. If a compressor is allowed to cycle after a fault is detected, there is a high probability that the compressor will be damaged and the system contaminated with debris from the failed compressor and decomposed oil. If current monitoring to the compressor is available, the system controller can take advantage of the compressor TOD and internal protector operation. The controller can lock out the compressor if current draw is not coincident with the contactor energizing, implying that the compressor has shut off on its internal protector. This will prevent unnecessary compressor cycling on a fault condition until corrective action can be taken.

Quiet Shut down

All scrolls in this size range have one of several types of “quiet” shutdown solutions. The ZR..KC/K3/ K4 Scrolls up to four tons use a cam-type device that separates the scrolls when they are driven backwards as high-pressure gas equalizes from the high side of the compressor to the low side during shutdown. Larger scrolls with 70 frame motors through ZR61 use a different type of cam that stops backward rotation during shut down. Models ZR68KC through ZR81KC

will continue to be built with the uid brake design,

so a momentary reverse rotation sound will be heard from these compressors. The newer ZR..KA scrolls incorporate a non dynamic discharge port check valve that prevents high pressure gas trapped in the dome from returning through the scroll set. All of these quiet shut down solutions allow the scroll compressor to restart immediately even if the system is not equalized eliminating the need for a time delay. Development testing should include a review of the shutdown sound for acceptability in a particular system. Also refer to section on “Brief Power Interruption”.

Discharge Check Valve

A low mass, disc-type check valve in the discharge tting

of the compressor prevents the high side, high pressure

discharge gas from owing rapidly back through the

compressor. This check valve was not designed to be

used with recycling pump down because it is not entirely leak-proof.

Motor Protector

Conventional internal line break motor protection is provided. The protector opens the common connection of a single-phase motor and the center of the Y connection on three-phase motors. The three-phase protector provides primary single-phase protection. Both types of protectors react to current and motor winding temperature.

Field Replacement of obsolete Single Phase ZR*K1 or ZR*K2 with Equivalent Capacity ZR*K3/K4/KA/ KC, Scroll Compressors

The discharge and suction tting sizes as well as the mounting foot pattern of the new models are identical to the ZR*K1 or ZR*K2. Tubing location is identical in

most cases for easy eld replacement. The ZR*K1

has an external top cap thermostat to limit discharge temperature. This feature has been replaced by the Therm-O-Disc® located inside the new scrolls. When replacing the ZR*K1, the top cap thermostat wires must be removed and the control circuit wires spliced together. See section on Compressor Replacement

after Motor Burn for further tips on eld replacement.

The replacement compressor will need a new run capacitor if the old capacitor is more than 5 microfarads different or the voltage rating of the old capacitor is lower than the new one. See compressor nameplate or Table 4 for recommended run capacitor. Note that the ZR*KA may only be used to replace compressors used for A/C, not heat pumps.

Application Considerations

The Copeland Scroll compressor has a number of application characteristics that are different from those of the traditional reciprocating compressor. These are detailed below.

Accumulators

The use of accumulators is very dependent on the application. The Copeland Scroll’s inherent ability to handle liquid refrigerant during occasional operating

ood back situations make the use of an accumulator

unnecessary in standard designs such as condensing

units. Applications, such as heat pumps with orice

refrigerant control, that allow large volumes of liquid

refrigerant to ood back to the compressor during

normal steady operation can dilute the oil to such an extent that bearings are inadequately lubricated and wear will occur. In such a case an accumulator must

be used to reduce ood back to a safe level that the compressor can handle. To test for ood back conditions

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and determine if the accumulator design is adequate, please see the section entitled Excessive Liquid Flood back Tests at the end of this bulletin. The accumulator

oil return orice should be from .040 to .055 inches (1 –

1.4 mm) in diameter depending on compressor size and

compressor ood back results. A large-area protective screen no ner than 30 x 30 mesh (0.6 mm openings) is required to protect this small orice from plugging. Tests have shown that a small screen with a ne mesh

can easily become plugged causing oil starvation to the compressor bearings.

Screens

The use of screens ner than 30 x 30 mesh (0.6mm

openings) anywhere in the system should not be used with these compressors. Field experience has

shown that ner mesh screens used to protect thermal

expansion valves, capillary tubes, or accumulators can become temporarily or permanently plugged with

normal system debris and block the ow of either oil or

refrigerant to the compressor. Such blockage can result in compressor failure.

Crankcase Heat - Single Phase

Crankcase heaters are not required on single phase compressors when the system charge is not over the 120% limit shown in Table 5. A crankcase heater is required for systems containing more than 120% of the compressor refrigerant charge limit listed in Table 5. This includes long line length systems where the extra charge will increase the standard factory charge above the 120% limit.

Experience has shown that compressors may ll with

liquid refrigerant under certain circumstances and

system congurations, notably after longer off cycles

when the compressor has cooled. This may cause excessive start up clearing noise or the compressor may lock up and trip on protector several times before starting. The addition of a crankcase heater will reduce customer noise and dimming light complaints since the compressor will no longer have to clear out liquid during start. Table 6 lists the crankcase heaters recommended for the various models and voltages.

Crankcase Heat – Three-Phase

A crankcase heater is required for three-phase compressors when the system charge exceeds the compressor charge limit listed in Table 5 and an accumulator cannot be piped to provide free liquid drainage during the off cycle (See Figure 2 and Table

6).

Pump down Cycle

A pump down cycle for control of refrigerant migration is not recommended for scroll compressors of this size.

If a pump down cycle is used, a separate external check valve must be added. The scroll discharge

check valve is designed to stop extended reverse rotation and prevent high-pressure gas from leaking rapidly into the low side after shut off. The check valve will in some cases leak more than reciprocating compressor discharge reeds, normally used with pump down, causing the scroll compressor to recycle more frequently. Repeated short-cycling of this nature can result in a low oil situation and consequent damage to the compressor. The low-pressure control differential has to be reviewed since a relatively large volume of gas will re-expand from the high side of the compressor into the low side on shut down.

Minimum Run Time

There is no set answer to how often scroll compressors can be started and stopped in an hour, since it is highly dependent on system configuration. Other than the considerations in the section on Brief Power Interruptions, there is no minimum off time because scroll compressors start unloaded, even if the system has unbalanced pressures. The most critical consideration is the minimum run time required to return oil to the compressor after startup. To establish the minimum run time obtain a sample compressor equipped with a sight tube (available from Emerson Climate Technologies) and install it in a system with the longest connecting lines that are approved for the system. The minimum on time becomes the time required for oil lost during compressor startup to return to the compressor sump and restore a minimal oil level that will assure oil pick up through the crankshaft. Cycling the compressor for a shorter period than this, for instance to maintain very tight temperature control, will result in progressive loss of oil and damage to the compressor. See Application Engineering Bulletin 171262 for more information on preventing compressor short cycling.

Reversing Valves

Since Copeland Scroll compressors have very high

volumetric efciency, their displacements are lower

than those of comparable capacity reciprocating compressors. As a result, Emerson recommends that the capacity rating on reversing valves be no more than 2 times the nominal capacity of the compressor with which it will be used in order to ensure proper operation of the reversing valve under all operating conditions.

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The reversing valve solenoid should be wired so that the valve does not reverse when the system is shut off by the operating thermostat in the heating or cooling mode. If the valve is allowed to reverse at system shutoff, suction and discharge pressures are reversed to the compressor. This results in pressures equalizing through the compressor which can cause the compressor to slowly rotate until the pressures equalize. This condition does not affect compressor durability but can cause unexpected sound after the compressor is turned off.

Low Ambient Cut-Out

A low ambient cut-out is not required to limit air-to-air heat pump operation. Air-to-water heat pumps must

be reviewed since this conguration could possibly run

outside of the approved operating envelope (Figure 5) causing overheating or excessive wear.

Oil Type

Several types of compatible mineral oils are used in the R-22 compressors. A standard 3GS oil may be

used if the addition of oil in the eld is required. See

the compressor nameplate for original oil charge. See Application Engineering bulletin 17-1248 for more information about oil types Emerson uses. A complete

recharge should be four uid ounces (118 ml) less than

the nameplate value. Some models have been released for use with R407C or 134a and use polyol ester oil,

identied as POE, along with the charge quantity on

the nameplate. These models have an “E” in the 7th place of the model number. An example would be the ZR24K3E-PFJ compressor. Copeland® Ultra 22 CC

should be used if additional oil is needed in the eld.

Mobil Arctic EAL22CC or ICI Emkarate RL32CF oil may be used to recharge these compressors if Ultra 22 is not available. Compressors charged with POE may be used with R-22 but compressors charged with mineral oil may not be used with HFC refrigerants such as 407C or 134a because they are not miscible.

Discharge Mufers

Flow through Copeland Scroll compressors is semicontinuous with relatively low pulsation. External

mufers, where they are normally applied to piston

compressors today, may not be required for Copeland Scroll. Because of variability between systems, however, individual system tests should be performed to verify acceptability of sound performance. When no testing is

performed, mufers are recommended in heat pumps. A hollow shell mufer such as the Alco APD-1 or APD- 054 will work quite well. The mufer should be located

a minimum of six inches (15 cm) to a maximum of 18 inches (46 cm) from the compressor for most effective

operation. The further the mufer is placed from the

compressor within these ranges the more effective it may be. If adequate attenuation is not achieved, use a

mufer with a larger cross-sectional area to inlet-area

ratio. The ratio should be a minimum of 20 to 1 with a

30 to 1 ratio recommended. The mufer should be from

four to six inches (10-15 cm) long.

Air Conditioning System Suction Line Noise and Vibration

Copeland Scroll compressors inherently have low sound and vibration characteristics. However, the sound and vibration characteristics differ in some respects from those of reciprocating compressors. In rare instances, these could result in unexpected sound complaints.

One difference is that the vibration characteristic of the scroll compressor, although low, includes two very close frequencies, one of which is normally isolated from the shell by the suspension of an internally suspended compressor. These frequencies, which are present in all compressors, may result in a low level “beat” frequency that may be detected as noise coming along the suction line into a house under some conditions. Elimination of the “beat” can be achieved by attenuating either of the contributing frequencies. The most important frequencies to avoid are line and twice-line frequencies for single-phase compressors and line frequency for three phase compressors. This is easily done by using one of the common combinations of design congurations described in Table 3. The scroll compressor makes both a rocking and torsional motion,

and enough exibility must be provided in the line to

prevent vibration transmission into any lines attached to the unit. In a split system the most important goal is to ensure minimal vibration in all directions at the service valve to avoid transmitting vibrations to the structure to which the lines are fastened.

A second difference of the Copeland Scroll is that under some conditions the normal rotational starting motion of the compressor can transmit an “impact” noise along the suction line. This may be particularly pronounced in three-phase models due to their inherently higher starting torque. This phenomenon, like the one described previously, also results from the lack of internal suspension, and can be easily avoided by using standard suction line isolation techniques as described in Table 3.

The sound phenomena described above are not usually associated with heat pump systems because of the isolation and attenuation provided by the reversing valve and tubing bends.

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Single Phase Starting Characteristics

Start assist devices are usually not required, even if a system utilizes non-bleed expansion valves. Due to the inherent design of the Copeland Scroll, the internal compression components always start unloaded even if system pressures are not balanced. In addition, since internal compressor pressures are always balanced at startup, low voltage starting characteristics are excellent for Copeland Scroll compressors. Starting current on

any compressor may result in a signicant “sag” in

voltage where a poor power supply is encountered. The low starting voltage reduces the starting torque of the compressor and subsequently increases the start time. This could cause light dimming or a buzzing noise where wire is pulled through conduit. The start components listed in Table 7 will substantially reduce start time and consequently the magnitude and duration of both light dimming and conduit buzzing.

PTC Start Components

For less severe voltage drops or as a start boost, solid

state Positive Temperature Coefcient devices rated

from 10 to 25 ohms may be used to facilitate starting for any of these compressors.

Electrical Connection

The orientation of the electrical connections on the Copeland Scroll compressors is shown in Figure 4. Three electrical connection options are available for these compressors. These include the “Molded Plug” one piece push-on connection, available in certain

markets, and “Quick Connect” ag termination available

on all scrolls of this size. Some four-ton and larger models also offer “T-block Screw Connection” for ring termination.

Deep Vacuum Operation

Scrolls incorporate internal low vacuum protection and will stop pumping (unload) when the pressure ratio exceeds approximately 10:1. There is an audible increase in sound when the scrolls start unloading.

Copeland Scroll compressors (as with any refrigerant compressor) should never be used to evacuate a refrigeration or air conditioning system. The scroll compressor can be used to pump down refrigerant in a unit as long as the pressures remain within the operating envelope shown in Figure 5. Prolonged operation at low suction pressures will result in overheating of the scrolls and permanent damage to the scroll tips, drive bearings and internal seal. (See AE24-1105 for proper system evacuation procedures.)

Nomenclature

The model numbers of the Copeland Scroll compressors include the approximate nominal 60 HZ capacity at standard operating conditions. An example would be the ZR24K3-TFD, which has 24,500 Btu/hr (7 kw) cooling capacity at the ARI high temperature air conditioning rating point when operated on 60 Hz. Note that the same compressor will have approximately 5/6 of this capacity or 20,200 Btu/hr (5.9 kw) when operated on 50 Hz current. Please refer to Online Product Information at www.emersonclimate.com for details.

Shell Temperature

Certain types of system failures, such as condenser or evaporator fan blockage or loss of charge, may

cause the top shell and discharge line to briey but

repeatedly reach temperatures above 350ºF (177ºC) as the compressor cycles on its internal protection devices. Care must be taken to ensure that wiring or other materials, which could be damaged by these temperatures, do not come in contact with these potentially hot areas.

Suction and Discharge Fittings

Copeland Scroll compressors have copper plated steel

suction and discharge ttings. These ttings are far more rugged and less prone to leaks than copper ttings

used on other compressors. Due to the different thermal properties of steel and copper, brazing procedures may have to be changed from those commonly used. See

Figure 6 for assembly line and eld brazing procedures.

Three Phase Scroll Compressors

Scroll compressors, like several other types of compressors, will only compress in one rotational direction. Direction of rotation is not an issue with single phase compressors since they will always start and run in the proper direction (except as described in the section “Brief Power Interruptions”). Three phase compressors will rotate in either direction depending upon phasing of the power. Since there is a 50-50 chance of connecting power in such a way as to cause rotation in the reverse direction, it is important to

include notices and instructions in appropriate locations on the equipment to ensure proper rotation direction is achieved when the system is installed and operated. Verification of proper

rotation direction is made by observing that suction pressure drops and discharge pressure rises when the compressor is energized. Reverse rotation will result in substantially-reduced current draw compared to normal values.

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There is no negative impact on durability caused by operating three phase Copeland Scroll compressors in the reversed direction for a short period of time (under one hour) but oil may be lost. After several minutes of reverse operation, the compressor’s internal protector will trip. If allowed to repeatedly restart and run in reverse without correcting the situation, the compressor will be permanently damaged because of oil loss to the system. Oil loss can be prevented during reverse rotation if the tubing is routed at least six inches (15 cm) above the compressor. All three-phase scroll compressors are wired identically internally. As a result,

once the correct phasing is determined for a specic

system or installation, connecting properly phased

power leads to the identied compressor electrical

(Fusite) terminals will maintain proper rotation direction. See Fig 4. It should be noted that all three phase scrolls will continue to run in reverse until the protector opens or the phasing is corrected.

Brief Power Interruptions

Brief power interruptions (less than 1/2 second) may result in powered reverse rotation of single-phase Copeland Scroll compressors. This occurs because high-pressure discharge gas expands backward through the scrolls during power interruption, causing the scroll to orbit in the reverse direction. When power is reapplied while reverse rotation is occurring, the compressor may continue to run in the reverse direction for some time before the compressor’s internal protector trips. This has no effect on durability. When the protector resets, the compressor will start and run normally.

To avoid disruption of operation, an electronic control that can sense brief power interruptions may be used to lock out the compressor for a short time. This control could be incorporated in other system controls (such as defrost or thermostat), or be a stand-alone control.

Functional specications for this control as well as a

suggested wiring diagram are shown in Figure 3.

Because three-phase models have high enough torque to prevent reverse rotation after power interruptions no time delay is necessary.

ASSEMBLY LINE PROCEDURES

Installing the compressor

Scroll compressors leave the factory dehydrated with a positive dry air charge. Plugs should not be removed from the compressor until the compressor has had

sufcient time to warm up if stored outside and is ready

for assembly to the unit. It is suggested that the larger

suction plug be removed rst to relieve the internal

pressure. Removing the smaller discharge plug could

result in a spray of oil out of this tting since some oil

would accumulate in the head of the compressor after Emerson test runs the compressor. The inside of both

ttings should we wiped with a lint free wipe to remove

residual oil prior to brazing. A compressor containing mineral oil should never be left open longer than 15 minutes or 5 minutes if it contains POE oil.

Assembly Line Brazing Procedure Figure 6 discusses the proper procedures for brazing

the suction and discharge lines to a scroll compressor.

It is important to ow nitrogen through the system

while brazing all joints during the system assembly process. Nitrogen displaces the air and prevents the

formation of copper oxides in the system. If allowed

to form, the copper oxide akes can later be swept

through the system and block screens such as those protecting capillary tubes, thermal expansion valves, and accumulator oil return holes. The resulting blockage of oil or refrigerant may do damage resulting in compressor failure.

Pressure Testing

The pressure used on the line to meet the UL burst pressure requirement can not be higher than 400 psig. Higher pressure might result in permanent deformation of the compressor shell and possibly cause rotor slip.

Assembly Line System Charging Procedure

Systems should be charged on both the high and low sides simultaneously. The majority of the charge should be placed in the high side of the system to prevent low

volt start difculties, Hipot failures, and bearing washout during rst-time start on the assembly line. It is best to

charge only vapor into the low side of the system. Do not operate compressor without enough system charge to maintain at least 7 psig (0.5kg/cm2) suction pressure. Do not operate with a restricted suction. Do not operate with the low pressure cutout disabled. Allowing pressure to drop below 7 psig

(0.5 kg/cm2) for more than a few seconds may overheat scrolls and cause early drive bearing damage. Do not use compressor to test opening set point of a high pressure cutout. Bearings are susceptible to damage before they have had several hours of normal running for proper break in.

“Hipot” (AC High Potential) Testing

Copeland Scroll compressors are congured with the

motor down and the pumping components at the top of the shell. As a result, the motor can be immersed in refrigerant to a greater extent than hermetic reciprocating compressors when liquid refrigerant is present in the shell. In this respect, the scroll is more like

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semi-hermetic compressors which can have horizontal motors partially submerged in oil and refrigerant. When Copeland Scroll compressors are Hipot tested with liquid refrigerant in the shell, they can show higher levels of leakage current than compressors with the motor on top. This phenomenon can occur with any compressor when the motor is immersed in refrigerant. The level of current leakage does not present any safety issue. To lower the current leakage reading, the system should be operated for a brief period of time to redistribute the refrigerant

to a more normal conguration and the system Hipot

tested again. See AE Bulletin 4-1294 for Megohm testing recommendations. Under no circumstances should the Hipot test be performed while the compressor is under a vacuum.

Final Run Test

Single phase scrolls with an electrical characteristic of “PFV” (208-230 volt, 1Ô, 60 Hertz) at the end of the model number may not be started at a voltage lower than 187 volts and must have a voltage no lower than 197 volts once the compressor is running under load.

Variable transformers used on assembly lines are often not capable of starting larger compressors at a particular voltage setting. To test for voltage sag during the initial

locked rotor starting phase the rst compressor in a

production run should be used to preset the voltage. Remove the start wire from the compressor and apply 200 volts to the compressor. With the start winding removed the compressor will remain in locked rotor long enough to read the voltage supply. If the voltage sags below the minimum guaranteed starting voltage the variable transformer must be preset to a higher voltage to start the compressor at a higher voltage.

Other compressor voltages. All other compressor voltages, both single and three phase are guaranteed to start and run at 10% below the lowest voltage shown on the nameplate.

Unbrazing System Components

Caution! Before opening a system it is important to remove all refrigerant from both the high and low side. If the refrigerant charge is removed from a

scroll-equipped unit by bleeding one side only, it is very possible that either the high or low side of the system remains pressurized. If a brazing torch is then used to disconnect tubing, the pressurized refrigerant and oil mixture could ignite when it escapes and contacts

the brazing ame. It is important to check both the high pressure and low pressure side with manifold gauges before unbrazing. Instructions should be

provided in appropriate product literature and assembly (line repair) areas. If compressor removal is required,

the compressor should be cut out of system rather than unbrazed. See Figure 6 for proper compressor removal procedure.

Copeland Scroll Functional Check

A functional compressor test during which the suction service valve is closed to check how low the compressor will pull suction pressure is not a good indication of how well a compressor is performing. Such a test will damage a scroll compressor. The following diagnostic procedure should be used to evaluate whether a Copeland Scroll compressor is functioning properly:

1. Proper voltage to the unit should be verified. Determine if the internal motor overload protector has opened or if an internal motor short or ground fault has developed. If the protector has opened,

the compressor must be allowed to cool sufciently

to allow it to reset.

2. Check that the compressor is correctly wired.

3. Proper indoor and outdoor fan/blower operation

should be veried.

4. With service gauges connected to suction and

discharge pressure ttings, turn on the compressor.

If suction pressure falls below normal levels the

system is either low on charge or there is a ow

blockage in the system.

5. Single Phase Compressors

If the compressor starts and the suction pressure does not drop and discharge pressure does not rise to normal levels, either the reversing valve (if so equipped) or the compressor is faulty. Use normal diagnostic procedures to check operation of the reversing valve.

Three Phase Compressors

If suction pressure does not drop and discharge pressure does not rise to normal levels, reverse any two of the compressor power leads and reapply power to make sure the compressor was not wired to run in reverse. If pressures still do not move to normal values, either the reversing valve (if so equipped) or the compressor is faulty. Reconnect the compressor leads as originally configured and use normal diagnostic procedures to check operation of the reversing valve.

6. To test if the compressor is pumping properly, the compressor current draw must be compared to published compressor performance curves using the operating pressures and voltage of the system. If the measured average current deviates more than ±15% from published values, a faulty compressor may be indicated. A current imbalance exceeding

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15% of the average on the three phases of a threephase compressor should be investigated further. A more comprehensive trouble-shooting sequence for compressors and systems can be found in Section H of the Emerson Climate Technologies Electrical Handbook.

7. Before replacing or returning a compressor: Be certain that the compressor is actually defective. As a minimum, recheck a compressor returned from

the eld in the shop or depot for Hipot, winding

resistance, and ability to start before returning to Emerson Climate Technologies. More than one-third of compressors returned to Emerson for warranty analysis are determined to have nothing found

wrong. They were misdiagnosed in the eld as

being defective. Replacing working compressors unnecessarily costs everyone.

Tandem Scroll Compressors The refrigerant charge limit for tandem compressors

is shown in Table 5. A three-phase unit with a charge over this limit must have crankcase heaters added to both compressors. The ZRT90 – ZRT122 compressors are mounted on rails using rubber mounting parts. The ZRT136 – ZRT162 compressors are rigidly mounted on rails using solid steel mounting parts. These mounts are installed at the factory and should not be loosened. Tighten to 125 inch pounds (14 NM) if it becomes necessary to tighten these mounts. Holes in the mounting rails may be used to mount isolation grommets under the entire tandem.

for liquid line lter-drier recommendations. It is highly recommended that the suction accumulator be replaced if the system contains one. This is because

the accumulator oil return orice or screen may be

plugged with debris or may become plugged shortly after a compressor failure. This will result in starvation of oil to the replacement compressor and a second failure.

Start-up of a New or Replacement Compressor

It is good service practice, when charging a system, to charge liquid refrigerant into the high side only and charge the low side of the system with vapor only. It is not good for any compressor to have liquid refrigerant dumped from a refrigerant cylinder into the crankcase of the compressor. Do not start the compressor while the system is in a deep vacuum. Internal arcing may occur when a scroll compressor is started in a vacuum.

Do not operate compressor without enough system charge to maintain at least 7 psig (0.5 kg/cm2) suction pressure. Do not operate with a restricted suction. Do not operate with the low pressure cut-out disabled. Allowing suction pressure to drop

below 7 psig (0.5 kg/cm2) for more than a few seconds may overheat scrolls and cause early drive bearing

damage. Never install a system in the eld and leave it

unattended with no charge, a holding charge, or with the service valves closed without securely locking out the system. This will prevent unauthorized personnel from accidentally operating the system for comfort cooling and potentially ruining the compressor by operating

with no refrigerant ow.

A discharge check valve must be placed in the common discharge line when pump down is used. Both compressors must be at the same level to prevent oil from migrating to the lowest compressor through the oil equalization line.

Compressors may be individually cycled. Individual

compressors should not be replaced in the eld. The

entire tandem compressor unit must be replaced if it becomes necessary to replace one compressor.

Individual compressors congured for tandem usage

may not be available for field replacement. See

section below for further tips on eld replacement of

compressors.

Compressor Replacement after Motor Burn

In the case of a motor burn, the majority of contaminated oil will be removed with the compressor. The rest of the

oil is cleaned through use of suction and liquid line lter dryers. A 100% activated alumina suction lter drier is

recommended but must be removed after 72 hours. See AE24-1105 for clean up procedures and AE11-1297

Excessive Liquid Flood back Tests

The following tests are for those system congurations and charge levels identied in Table 1 that need special

testing to verify exemption from need of an accumulator. Figure 1 should be used to determine the effectiveness of an accumulator. The compressor sump temperature during any test where the return gas superheat is near zero must always meet the guidelines of Figure 1.

To test for excessive continuous liquid refrigerant ood back, it is necessary to operate the system in a test

room at conditions where steady state ood back may

occur (low ambient heating operation). Thermocouples should be attached with glue or solder to the center of the bottom shell and to the suction and discharge lines approximately 6 inches (15 cm from the shell). These thermocouples should be insulated from the ambient air with Permagum® or other thermal insulation to be able to record true shell and line temperatures. If the system

is designed to be eld charged, it should be overcharged

by 15% in this test to simulate overcharging commonly

found in eld installations.

AE4-1312 R2

The system should be operated at an indoor temperature of 70°F (21°C). and outdoor temperature extremes (0°F

or -18°C or lower in heating) to produce ood back

conditions. The compressor suction and discharge pressures and temperatures as well as the sump temperature should be recorded. The system should be allowed to frost up for several hours (disabling the defrost control and spraying water on the outdoor coil may be necessary) to cause the saturated suction temperature to fall to below -10°F (-23°C). The compressor sump temperature must remain above the sump temperature shown in Figure 1 or design changes

must be made to reduce the amount of ood back. If an accumulator is used, an oil return orice size of 0.040

- .055” (1 - 1.4 mm) is recommended. (See information

on Accumulators in Application Considerations and also AE11-1247). Increasing indoor coil volume, increasing

outdoor air ow, reducing refrigerant charge, decreasing

capillary or orifice diameter, and adding a charge compensator can also be used to reduce excessive

continuous liquid refrigerant ood back.

To test for repeated excessive liquid ood back during normal system off-cycles perform the “Field Application Test”. Obtain a sample compressor with a side sight tube to measure liquid level in the

compressor. Set the system up in a conguration with

the indoor unit elevated several feet above the outdoor unit with twenty-five feet (8 meters) of connecting tubing with no traps between the indoor and outdoor

units. If the system is designed to be eld charged,

the system should be overcharged by 15% in this

test to simulate overcharging commonly found in eld

installations. Operate the system in the cooling mode at the outdoor ambient, on/off cycle times, and number of cycles specied in Table 2. Record the height of the liquid in the compressor at the start of each on cycle, any protector trips, or any compressor stalls during each test. Review the results with Emerson Climate Technologies Application Engineering to determine if an accumulator is required for the application. The criteria for pass/fail is whether the liquid level reaches

the height of the scroll compressor suction tting on the

side of the shell. Liquid levels higher than the suction

tting will allow compressor oil oating on top of the

refrigerant to be ingested by the scrolls and pumped out of the compressor.

AE4-1312 R2

Liquid Level

Drainage In Off Cycle

Scroll

Accumulator

200°F Maximum Oil Temperature

100

Oil Dilution Chart

80 70

Safe Area

OK. See Note 1

60 50

°F

40 30

Unsafe Area. Too Much Refrigerant Di lution

20 10

Compressor Sump Temperatur

-10010 20 30 40 50

Evaporating Temperature °F

Figure 1

Note 1: Operation in this refrigerant dilution area is safe in air to air heat pump heating mode. For other applications, such as AC only, review expansion device to raise superheat. A cold sump may result in high refrigerant migration after shut down.

Figure 2

To prevent ooded start damage on 3 phase scrolls due to off cycle migration, the accumulator may be congured on some systems to allow free drainage from the compressor to the accumulator during the off cycle. When the above conguration is not possible and the unit charge is over the charge limit shown

in Table 5, a crankcase heater is required.

230/240 VAC

AE4-1312 R2

Fuse

Typical Solid State Timer

(if used)

Note: Wire A-B

NOT required

is when optional timer is used

System Operating Thermostat

Other Protective Devices (if used)

Discharge Line Thermostat (if used)

Compressor Contactor

Condenser Fan Contactor

(if used)

Time Delay Relay Specifications

Timer Opens1 Electrical cycleTimer Closes Greater than 5 seconds later

(.016 sec. with 60 HZ operation) power is restored or not

after power is removed

Figure 3

T1,C

T2,S

T3,R

Terminal (Fusite) Connection

100

110

120

130

140

150

160

170

-20-10 0102030405060

Condensing Temp. (

Evaporating Temp. (°C)

Condensing Temp. (°F)

Evaporating Temp. ( °F)

R22 Scroll Operating Envelope

-20

-15

-10-50510

-25 15

ZR__KA

Limited

Envelope

All Other Scroll Products

Motor Terminal (Fusite) Connections

Figure 4

AE4-1312 R2

Figure 5

}

Scroll Suction Tube Brazing

AE4-1312 R2

New Installations

• The copper-coated steel suction tube on scroll compressors can be brazed in approximately the same manner as any copper tube.

• Recommended brazing materials: Any silfos material is recommended, preferable with a minimum of 5% silver. However, 0% silver is acceptable.

• Be sure suction tube tting I.D. and suction tube O.D. are clean prior to assembly. If oil lm

is present wipe with denatured alcohol, Dichlo-

ro-Triuoroethane or other suitable solvent.

• Using a double-tipped torch apply heat in Area

1. As tube approaches brazing temperature,

move torch ame to Area 2.

• Heat Area 2 until braze temperature is attained, moving torch up and down and rotating around tube as necessary to heat tube evenly. Add braze material to the joint while moving torch around joint to ow braze material around circumference.

• After braze material ows around joint, move

torch to heat Area 3. This will draw the braze material down into the joint. The time spent heating Area 3 should be minimal.

• As with any brazed joint, overheating may be

detrimental to the nal result.

Field Service

• To disconnect: Reclaim refrigerant from both the high and low side of the system. Cut tubing near compressor.

• To reconnect:

• Recommended brazing materials: Silfos with minimum 5% silver or

silver braze material with ux.

• Insert tubing stubs into tting and

connect to the system with tubing connectors.

• Follow New Installation brazing instructions.

Figure 6

AE4-1312 R2

Operating Principle of Scroll

Figure 7

AE4-1312 R2

Non-Bleed

TXV

Non-Bleed

TXV

Other (1)

Not

Required

Not

Required

Other (1)

Required

Not

Required

Not

Required

Not

Required

Not

Required

Other (1)

Nominal

System

Charage

(2)

Table 1

Scroll Compressor Application Diagram

(1) “Other” includes bleed-type TXVs, capillary tubes, and xed orices.

(2) “Nominal System Charge” is dened as the design charge for a system.

Note: See text for crankcase heater requirements.

*120% Times Compressor refrigerant charge limit in Table 5.

Table 2

Field Application Test

Operate the system as it would be operated in an actual eld installation, cycling the

unit on and off for the times indicated at each ambient.

Outdoor Ambient 85°F (29°C) 95°F (35°C) 105°F (40°C)

System On-Time (Minutes) 7 14 54 System Off-Time (Minutes) 13 8 6

Number of On/Off Cycles 5 5 4

Table 3

Recommended Conguration

Component Description

Tubing Conguration Shock loop Service Valve “Angled valve” fastened to unit Suction mufer Not required

Alternate Conguration

AE4-1312 R2

Component Description

Tubing Conguration Shock loop Service Valve “Straight through” valve not fastened to unit Suction mufer May be required (Acts as dampening mass)

Table 4

Recommended Run Capacitors for Field Replacement

of a ZR*K1 or K2 with a ZR*K3, K4, or KC

K1 *K2 K3 K4 KC

ZR18 25µf/370 volt 30µf/370 volt 35µf/370 volt 30µf/370 volt ZR23 30µf/370 volt 40µf/370 volt 35µf/370 volt 35µf/370 volt ZR26 35µf/370 volt 40µf/370 volt 30µf/440 volt ZR28 35µf/370 volt 45µf/370 volt 35µf/440 volt ZR34 35µf/440 volt 50µf/370 volt 40µf/370 volt ZR40 35µf/440 volt 55µf/370 volt 40µf/440 volt ZR46 40µf/440 volt 60µf/370 volt ZR49 40µf/440 volt 60µf/370 volt 45µf/440 volt ZR57 55µf/440 volt 80µf/370 volt 60µf/370 volt ZR61 55µf/440 volt 80µf/370 volt 60µf/370 volt

Table 5

Compressor Refrigerant Charge Limits

AE4-1312 R2

Model Frame Size*

Charge Limit 120% x Limit **

Pounds kg Pounds kg

ZR16-ZR29KC 53 6 2.7 7.2 3.24

ZR16-ZR24K4 53 6 2.7 7.2 3.24

ZR26-ZR48KC 63 8 3.6 9.6 4.32

ZR18-ZR48K3 63 8 3.6 9.6 4.32

ZR54-ZR81KC 70 10 4.5 12.0 5.40

ZR54-ZR61K3 70 10 4.5 12.0 5.40 ZR16-ZR34KA 53 8 3.6 9.6 4.32 ZR38-ZR54KA 63 10 4.5 12.0 5.40

TANDEM 63 10 4.5 12.0 5.40 TANDEM 70 12 5.5 14.4 6.60

*Approximate Shell Diameter (e.g. 63 = 6.5 Inches) ** Charge Allowance for system

Table 6

Crankcase Heaters

Copeland® Model

ZR16KC/4 - ZR29KC/4

ZR16KA - ZR34KA

Frame

Size

Emerson Part # Volts Watts Tutco Part # Leads

53 018-0052-00 240 40 02-6319-00 21” 53 018-0052-01 120 40 02-6319-02 21” 63 018-0041-00 240 40 02-6307-00 21” 63 018-0041-01 120 40 02-6307-02 21”

ZR18K3 - ZR48K3

ZR26KC - ZR48KC

ZR38KA - ZR54KA

63 018-0041-02 480 40 02-6307-03 21” 63 018-0041-03 575 40 02-6307-06 21” 63 018-0041-04 240 40 02-6311-00 48” 63 018-0041-05 480 40 02-6311-03 48” 63 018-0041-06 240 40 02-6313-00 32” 70 018-0057-00 240 70 02-6332-00 21” 70 018-0057-01 480 70 02-6332-03 21”

70 018-0057-02 575 70 02-6332-06 21” ZR54K3 - ZR61K3 ZR54K3 - ZR81KC

018-0057-03 240 70 02-6334-00 32” 018-0057-04 240 70 02-6335-00 48”

All 018-0057-XX

Heaters t both 63 and

70 frame* shells

63 & 70

018-0057-05 480 70 02-6335-03 48” 018-0057-06 575 70 02-6335-06 48” 018-0057-07 120 70 02-6335-02 48” 018-0057-08 400 70 02-6335-12 48” 018-0057-09 277 70 02-6332-04 21”

*Approximate Shell Diameter (e.g. 70 = 7.3 Inches)

Table 7

Approved Start Components for Scroll Compressors

AE4-1312 R2

Model MFD Volts

ZR16K(x) to

ZR48K(x)-PFV

ZR46K(x) to

ZR68K(x)-PFV

88-108 330 014-0036-03 3ARR3CT3P5 040-0001-79 170-180 40-90 332

270-324 330 014-0006-10 3ARR3CT3P5 040-0001-79 170-180 40-90 332

Part

Number

G.E. p/n Emerson p/n

x = C, 3, 4 or CE, 3E, 4E (ZR_KA Start components still in development)

Pick-up

Volts

Drop-out

Volts

Coil

Voltage

Emerson ZR16-29KC, ZR16-24K4, ZR16-34KA, ZR38-54KA, ZR18-48K3 Application Engineering Bulletin

Specifications and Main Features

Frequently Asked Questions

User Manual