Emerson AE4-1287 User Manual

AE4-1287 R8 September 2019

Copeland Discus™ Compressors with Demand Cooling™ System

TABLE OF CONTENTS

Section Page Section Page

Safety Figures and Tables

Safety Instructions ................................................... 2

Safety Icon Explanation ........................................... 2

Instructions Pertaining to Risk of Electrical

Shock, Fire, or Injury to Persons ............................ 3

Safety Statements ................................................... 3

Introduction ............................................................... 4

Updated Discharge Temperature Guidelines ............ 4

Operating Range ..................................................... 4

Demand Cooling System ......................................... 4

Demand Cooling System Design ............................. 5

Demand Cooling Compressors ................................ 5

Condenser Sizing .................................................... 5

Demand Cooling System Components .................... 5

™

Demand Cooling with CoreSense

System Information .................................................. 6

Demand Cooling with Discus

Unloading .............................................................. 6

4D and 6D Unloading with Demand Cooling ............ 7

3D Copeland Discus Digital

Demand Cooling ................................................... 7

Performance Adjustment Factors ............................. 7

Demand Cooling Specifications ............................... 7

™

Protection ......... 6

™

Compressor

compressors with

Demand Cooling System ......................................... 7

Low Temperature Operating Envelopes With and

Without Demand Cooling .................................... 8

CoreSense™ Discharge Temperature Protection ..... 8

Standard Location of CoreSense

Temperature Probe ............................................ 9

Low Temperature Operating Envelope for R-22 at

65°F Return Gas (with Head Fan) .................... 9

Demand Cooling System Diagram ......................... 10

Demand Cooling Wiring Schematics ................. 11-13

Demand Cooling Operating Setpoints and

Control Actions ..................................................... 14

Demand Cooling Kit Part Numbers ........................ 14

Appendix - Demand Cooling Diagnostics ....... 15-18

AE4-1287 R8

Safety Instructions

Copeland Discus Particular emphasis has been placed on the user's safety. Safey icons are explained below and safety instructions applicable to the products in this bulletin are grouped on page 3. These instructions should be retained throughout the lifetime of the compressor. You are strongly advised to follow these safety instructions.

™

compressors are manufactured according to the latest U.S. and European Safety Standards.

Safety Icon Explanation

DANGER

DANGER indicates a hazardous situation which, if not avoided, will result in death or serious injury.

WARNING

CAUTION

NOTICE

CAUTION

WARNING indicates a hazardous situation which, if not avoided, could result in death or serious injury.

CAUTION, used with the safety alert symbol, indicates a hazardous situation which, if not avoided, could result in minor or moderate injury.

NOTICE is used to address practices not related to personal injury.

CAUTION, without the safety alert symbol, is used to address practices not related to personal injury.

AE4-1287 R8

Instructions Pertaining to Risk of Electrical Shock, Fire, or Injury to Persons

WARNING

ELECTRICAL SHOCK HAZARD

• Disconnect and lock out power before servicing.

• Discharge all capacitors before servicing.

• Use compressor with grounded system only.

• Molded electrical plug must be used when required.

• Refer to original equipment wiring diagrams.

•

• Failure to follow these warnings could result in serious personal injury.

PRESSURIZED SYSTEM HAZARD

• System contains refrigerant and oil under pressure.

• Remove refrigerant from both the high and low compressor side before removing compressor.

•

• Never install a system and leave it unattended when it has no charge, a holding charge, or with the service valves closed without electrically

locking out the system.

• Use only approved refrigerants and refrigeration oils.

• Personal safety equipment must be used.

• Failure to follow these warnings could result in serious personal injury.

BURN HAZARD

• Do not touch the compressor until it has cooled down.

• Ensure that materials and wiring do not touch high temperature areas of the compressor.

• Use caution when brazing system components.

• Personal safety equipment must be used.

• Failure to follow these warnings could result in serious personal injury or

property damage.

CAUTION

Safety Statements

• Refrigerant compressors must be employed only for their intended use.

• install, commission and maintain this equipment.

•

• All valid standards and codes for installing, servicing, and maintaining electrical and refrigeration equipment must be observed.

COMPRESSOR HANDLING

• Use the appropriate lifting devices to move compressors.

• Personal safety equipment must be used.

• Failure to follow these warnings could result in personal injury or property damage.

AE4-1287 R8

Introduction

Energy efficiency regulations drive continuous change in the availability of refrigerants to the marketplace. With the introduction of R-22 as a replacement for R-502, compressors began to experience internal discharge temperatures that exceed the safe operational limits for long term stability of refrigerant oil. In response to this, Demand Cooling was developed as a reliable method to keep discharge temperatures reduced to a safe level without inhibiting the operating limits of the compressor. With the phase out of R-22, the following refrigerants have become viable alternatives for R-22 applications: R-407A, R-407C, R-407F, R-448A, R-449A. All of the above mentioned refrigerants require special attention to discharge temperature control.

CAUTION

POE may cause an allergic skin reaction and must be handled carefully and the proper protective equipment (gloves, eye protection, etc.) must be used when handling POE lubricant. POE must not come into contact with any surface or material that might be harmed by POE, including without limitation, certain polymers (e.g. PVC/ CPVC and polycarbonate). Refer to the Safety Data Sheet (SDS) for further details.

Updated Discharge Temperature Guidelines

Emerson Climate Technologies developed and released the Demand Cooling Discus applications with high discharge temperatures such as the R-22 low temperature refrigeration applications. Without Demand Cooling, these high temperatures typically resulted in overheating of the lubricant leading to compressor failures.

Since additional refrigerant solutions such as R-407A, R-407C, R-407F, R-448A, and R-449A became available to the marketplace, there have been numerous requests to operate Discus compressors without Demand Cooling in applications where it is possible to control both condensing temperature and the return gas temperature to low enough levels to avoid overheating related failures. Emerson Climate has re-evaluated operating guidelines for these refrigerants for the following reasons:

1. R-407A/C/F, R-448A/R-449A discharge temperatures are higher than R-404A, but lower

2. Many new refrigeration systems operate at lower compressor superheat/return gas temperatures

™

compressors to provide a solution for

than R-22.

system for Copeland

than AHRI rating condition at 65°F return gas.

3. Since February 2011, Copeland Discus compressors come standard with more comprehensive compressor protection via CoreSense™ technology

Due to these factors, Emerson is pleased to offer updated operating envelopes and guidelines for low temperature R-407A/C/F and R-448A/R-449A applications. For details on specific applications with Demand Cooling and without Demand Cooling, refer to page 8 of this bulletin.

Operating Range

Demand Cooling is designed to protect the compressor from high discharge temperatures over the evaporating and condensing temperature ranges shown in Figures 2, 3, and 6. Additionally, in instances where compressor return gas temperature and condensing temperature is closely controlled, the envelope in Figure 2 is achievable without the addition of Demand Cooling components to the compressor.

Demand Cooling System

Demand Cooling is compatible with single (conventional) units as well as parallel racks.

The Demand Cooling module uses the signal of a discharge head temperature sensor to monitor discharge gas temperature. If a critical temperature is reached, the module energizes a long life injection valve which meters a controlled amount of saturated refrigerant into the compressor suction cavity to cool the suction gas. This process controls the discharge temperature to a safe level. If, for some reason, the discharge temperature rises above a preset maximum level, the Demand Cooling module will turn the compressor off (requiring a manual reset) and actuate its alarm contact. To minimize the amount of refrigerant which must be injected, the suction gas cooling process is performed after the gas has passed around and through the motor.

Injection valve orifices have been carefully chosen for each body style to be large enough to provide the necessary cooling when required but not so large that dangerous amounts of liquid are injected, or that excessive system pressure fluctuation occurs during injection valve cycling. Normally, pressure fluctuations are no greater than 1 to 2 psi. It is important to use the correct valve for each compressor body style.

AE4-1287 R8

Performance data for Demand Cooling compressors includes the effects of injection when it is required. The approximate conditions where injection occurs are shown in where Demand Cooling is operating, the performance values are time averages of the instantaneous values, since small fluctuations in suction and discharge conditions occur as the Demand Cooling injection valve cycles.

Demand Cooling System Design

When Demand Cooling operates, it 'diverts' refrigeration capacity in the form of injected saturated refrigerant from the evaporator to the compressor (See Figure 7 for a typical single system schematic). The effect of this diversion on evaporator capacity is minimal because the diverted capacity is used to cool the gas entering the compressor. As the gas is cooled, it naturally becomes more dense, increasing the mass flow through the compressor, which partly compensates for the capacity diverted from the evaporator.

If there is substantial heat gain along the suction line, injection may result in a substantial loss in evaporator capacity during Demand Cooling operation. In order to minimize this loss, good practice indicates Demand Cooling operation be kept to a minimum through proper system design and installation practices. There are three areas which can be addressed to minimize the impact of Demand Cooling operation on performance.

1. Compressor Return Gas Temperature: Suction lines should be well insulated to reduce suction line heat

gain. Return gas superheat should be as low as possible consistent with safe compressor operation.

Figures 2, 3,

and

. At the conditions

temperature Discus CFC-502 compressors have been modified for use with R-22, R-407 A/C/F, or R-448A/449A and Demand Cooling. The modifications are the addition of an injection port on the compressor body and a temperature sensor port in the head of the compressor. The locations of these ports are critical and were determined through an extensive development program.

The R-22, R-407 A/C/F, or R-448A/449A rating data includes the effects of Demand Cooling injection when operating conditions require it based on 65 °F return gas.

Condenser Sizing

Condensers should be sized using conventional methods. Demand Cooling has virtually no effect on system heat of rejection.

Demand Cooling System Components

The Demand Cooling System (see Figure 1) consists of: The Demand Cooling Temperature Sensor (TS), The Demand Cooling Module (CM), and the Injection Valve (lV).

The TS uses a precision Negative Temperature Coefficient (NTC) Thermistor (thermistor resistance drops on temperature rise) to provide temperature signals to the CM.

The IV meters refrigerant flow from the liquid line to the compressor. The IV solenoid receives on-off signals from the CM. When compressor cooling is required the solenoid is energized and opens the IV orifice to deliver saturated refrigerant to the compressor for cooling. The valve orifice is carefully sized to meet the requirements of each body style of Discus compressors.

2. Condensing Temperatures: It is important when using R22, R-407 A/C/F, or R448A/449A as a low temperature refrigerant that condensing temperatures be minimized to reduce compression ratios and compressor discharge temperature.

3. Suction pressure: Evaporator design and system control settings should provide the maximum suction pressure consistent with the application in order to have as low a compression ratio as possible.

Demand Cooling Compressors

No new compressor models have been introduced for Demand Cooling. Instead, existing low

The CM has three functional groups:

A. The

B. The

Input signal and calculator circuits

compare the temperature sensor input signal to an internal set-point and decide whether to energize the IV solenoid or, in the case of a problem, the CM alarm relay.

output signal to the IV

an electronic switch connected to the IV solenoid so that, when required, refrigerant vapor can be metered to the compressor to prevent compressor overheating. One side of the electronic switch is connected internally to 'L1' and the other side to output terminal 'S' (see Figure 6).

is controlled by

AE4-1287 R8

C. The alarm signal for local or remote control. The alarm relay is energized, after a one minute

delay, by a continuous, low or high TS temperature signal. An alarm signal can indicate the following:

1. Compressor discharge temperature has risen above the level designed to be

controlled by Demand Cooling.

2. A shorted sensor.

3. An open sensor.

communicated to the CoreSense Protection module. See Figure 8E.

System Information

1. Demand Cooling is designed to work on all Copeland Discus compressors equipped with injection ports. A different kit is required for each compressor body style and control voltage. See Table 2 for a listing of Demand Cooling Kit part numbers.

In order to avoid nuisance trips, a one minute time delay is provided before alarm after a continuous high or low resistance reading or over temperature condition.

The alarm relay uses a single-pole-double-throw contact. The contact terminals are 'L', 'M', and 'A':

'L' - Common (to 'A' and 'M')

'L - M' - Normally Closed (compressor run. open on alarm)

'L - A'

The Normally Closed (NC) contact of the alarm relay ('L' to 'M') should be wired in the compressor contactor control circuit so that opening this contact removes the compressor from the line and removes power to the CM. See Figures 5A, B, C, and D.

Figures relay

employing internal over current protection. The current sensing relay is already included when using CoreSense protection) and Sentronic

oil pressure switch. The control circuit is purposely arranged so that an internal overload protector trip removes power to both the Sentronic™ and the Demand Cooling module. This precaution prevents the oil pressure switch from timing out and the Demand Cooling solenoid from injecting when the compressor is not operating.

The alarm relay requires a manual reset in order to call attention to a system problem.

Demand Cooling with CoreSense Protection

CoreSense Protection is compatible with Copeland Demand Cooling. However, the discharge temperature protection is provided by the Demand Cooling module. Discharge temperature information will not be

- Normally Open (alarm signal, close on

alarm)

5 A

and B also show a current sensing

(which must be used with compressors

™

2. The system must be clean. A dirty system may

have foreign material that can lodge in the solenoid

orifice. Always install a liquid line filter dryer in the injection valve inlet line capable of removing particles as small as 25 microns.

3. Do not use any filters containing materials that can leave the filter and possibly clog the IV orifice.

4. The liquid refrigerant supply line must be a minimum of 3/8" and routed so it will not interfere with compressor maintenance. Liquid refrigerant must have sufficient subcooling at the injection valve to prevent flashing upstream of the valve.

5. The liquid refrigerant supply line to the IV must be

supported so that it does not place stress on the

IV and IV tubing or permit excess vibration. Failure to make this provision may result in damage to the IV and its tubing and/or refrigerant loss.

6. A head fan must be used to help lower compressor

discharge temperatures for compressors using

HCFC-22. Return gas temperatures must NOT exceed 65°F.

7. System designers are advised to review their defrost schemes to avoid floodback to the compressor which may occur at defrost termination with R-22, R-407 A/C/F, or R-448A/449A. These refrigerants have a significantly higher heat of vaporization than does CFC-502, and if the same design parameters used with CFC-502 are used, floodback may occur.

Demand Cooling with Discus Compressor Unloading

Demand Cooling has been approved with unloading for 4D, 6D and 3D Copeland Discus Digital™. Demand Cooling has NOT been approved for 3D Moduload.

Note:

For Discus compressors with CoreSense

Diagnostics with the build of material

(BOM)

+ 12 hidden pages

Emerson AE4-1287 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual