Copeland Screw TM Compressors

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1 Copeland Screw TM Compressors Mechanical Guidelines for SHL & SHM Models using ESC-201 Control System Contents: Start-Up Procedure Operating Specifications Maintenance Trouble Shooting Guidelines

2 Start-up Procedures Factory Checks 1. General testing of the rack control circuit. 2. Test the safety inputs and alarm outputs on each of the ESC 201 s. (See the ESC 201 Form No manual for the individual test procedures). 3. Pressurize the rack and check for leaks. Start-up Procedure 1. Charge the oil separator and oil cooler(s) with the specifi ed oil for the system. 2. Energize the rack control circuit and energize the oil separator heaters (Temperature range for the heater operation is on at 100 F off at 125 F) 12 to 24 hours prior to startup. 3. Close the ball valve between separator and condenser. Then open up the oil line ball valves to each of the compressors. Taking one compressor at a time, open the oil solenoid valve (by jumping it out). Pressurize the oil separator with refrigerant. Observe the oil line sight glass; when you see oil entering the sigh glass, de-energize the oil line solenoid valve. This is very important for open drive screw compressors; the above procedure will help prevent damage to the compressor s shaft seal. After all the compressor oil lines have been charged the ball valve between the separator and condenser can be reopened. 4. For open drive compressors only. Check the couplings for the proper installation and that the keys have been installed properly; check the set screws for tightness. 5. Select one compressor on the rack to charge the system with refrigerant. 6. With a set of pressure gauges, place the low pressure gauge on the compressor suction and the high pressure on the discharge side of the compressor. Open the suction service valve one quarter of the way. Open the discharge service valve all the way. As the system charge increases open the suction service valve the rest of the way. 7. Start the compressor; one of the following observations could be made on the gauges. The fi rst could be a drop in the suction gauge with a rise in the discharge; this indicates the compressor running in the proper direction. The other observation could be the suction gauge rises and the discharge remains at the same level as before the compressor was started. This indicates that the compressor is running in reverse. Also you should have a rotation alarm on the ESC 201, this indicates that the rotation switch has opened up. To correct an improper rotation condition the following changes must be performed. First swap two phases around on the power conductor for that compressor. The next item that will have to be corrected is the phase leads to the ESC 201. The corresponding leads to the power conductors will need to be swapped at the ESC 201 phase connections. 8. Restart the compressor; the ESC 201 should check ok after 2 seconds the oil and economizer solenoid valve terminals C9 and C11 will be energized. 9. The safety functions for the compressor should be rechecked to insure that all of the safeties are working properly between the compressor and the ESC 201. Please refer to the ESC 201 manual for the proper method for testing the compressor safeties. Repeat steps 7 through 9 for each of the compressors on the rack. Please note that the suction service valves on the rest of the compressors may be opened up all the way. 1

3 Operating Specifications Screw Compressor Oil System Maximum oil temperature entering compressor R22 R404A/R507 R134a 130 F 140 F 140 F Minimum temperature exiting cooler 100 F Maximum oil pressure differential across the oil fi lter* 25 psi (alarm only) 35 psi oil fl ow switch (cut-out) Minimum differential across each compressor 90 psi oil fl ow switch cut-out (suction to discharge pressure) Motor Cooling Per Compressor Maximum motor temperature* (read from thermistor) 212 F Liquid injection None required Discharge Temperature Per Compressor Maximum discharge temperature* 212 F cut-out Normal discharge temperature 180 F Minumum discharge temperature Reverse Rotation Protection Per Compressor Pressure switch low discharge pressure* Phase sequencing* Proper sequence of phases to ESC 201 < 35º above condensing temperature 30 psi cut-in 20 psi cutout according to motor lead termination Suction Gas Temperature Open drive screw compressors Low temp. Medium temp. 40 F maximum superheat 30 F maximum superheat Semihermetic screw compressors Low temp. Medium temp F return gas temp F return gas temp. Subcooling Liquid Temperature Values The subcooled liquid temperature is dependent upon TXV selection for cases or evaporators and insulation quality of the liquid lines. Refer to the case or evaporator manufacturer for the allowable liquid temperature to the equipment. To correct the compressor capacity and power for the recommended liquid temperature; please refer to he economizer system and capacity control section of the screw manual. Economizer Superheat Temperature Values ECO port superheat superheat *ESC 201 control function 2

4 Maintenance Item Inspection Frequency of Maintenance Oil Filter Element Oil Flow Switch Compressor Power Connections Compressor Contactor Connections Compressor Breaker Connections Control Circuit Terminations Check Pressure Drop Reference Section A. Trouble Shooting Guidelines Check for Proper Operation Reference Section J. Trouble Shooting Guidelines Check for Tightness, Frayed Wires Reference Section N. Trouble Shooting Guidelines Check for Tightness, Frayed Wires Reference Section N. Trouble Shooting Guidelines Check for Tightness, Frayed Wires Reference Section N. Trouble Shooting Guidelines Check for Tightness, Frayed Wires Reference Section N. Trouble Shooting Guidelines Three Month Intervals High Pressure Bearings Check Bearings for Excessive Play 50,000 to 80,000 Lateral Movement Should be Less Than in. Hours of Run Time Oil Sampling Have Sample Tested by a Qualifi ed Facility One Year Intervals Trouble Shooting Guidelines A. Oil Filter; The Filter Will Alarm Under The Following Conditions: Oil fl ow switch which will not close when the compressor is started. When the pressure across the filter exceeds 25 psi. This condition most likely will occur within weeks or months of the system start-up. A malfunctioning or miswired switch will also cause the ESC 201 to alarm. To verify that the switch is malfunctioning or miswired, the fi lter element must be changed or the connections must be verifi ed that the switch is wired normally open. Reset the ESC 201 to see if the alarm can be cleared. B. Oil Flow; The Flow Switch Will Alarm Under The Following Conditions: Loss of differential in the system which could occur when the head pressure drops too low. The differential cannot drop below 90 psi. An inoperative oil solenoid valve which will not open. An obstruction within one of the screened orifi ces in the compressor. An excessive amount of refrigerant contained in the oil line of the compressor. C. Oil Level; The Oil Level Switch Will Alarm Under The Following Conditions: An excessive amount of refrigerant in the oil separator causing the separator to foam up during this situation. This can occur if too much liquid is coming from a TXV that could be out of adjustment or has malfunctioned. A large pressure drop on the discharge side of the separator occurs. This situation can take place with heat reclaim coils or split condensers. 3

5 D. Rotation; The Rotation Switch Will Alarm Under The Following Situation: Pressure in the dishcharge area of the rotor chamber does not reach at least 70 PSI. A 5 VAC signal is not being sent back to terminal A7 from terminal A3. Check for proper wiring and for a 5 VAC signal across the switch. E. Run Proof; The Run Proof Will Alarm Under The following Conditions: The run proof will not close during the starting of the compressor. The run proof is lost during the operation of the compressor. F. Motor Overload Temperature; The Motor Overload Will Alarm Under The Following Conditions: Locked rotor conditions:this condition could occur if the rotors are locked due to excessive oil in the compressor or debris has lodged in the rotors. Over or under voltage condition within the electrical system. Malfunctioning temperature sensor. To check the sensor measure the DC voltage on the ESC 201 (points B1 and B7). The voltage across these points will read.4 to.6 VDC for a good sensor if the voltage reads 2.3 VDC or above the sensor is open. G. Discharge Temperature Sensor; This Alarm Will Occur Under The Following Conditions: When the discharge temperature exceeds 212 Fahrenheit. The cause for high discharge temperature is generally due to high oil temperatures entering the compressor. Malfunctioning sensor: To check the sensor measure discharge gas temperature at the outlet of the compressor. If the temperature is below 212, the sensor is bad. H. Phase Protection; The Phase Protection Alarm Will Occur Under The Following Circumstances: Power conductors that are improperly sequenced to the compressor. This normally occurs at start-up when the electrical contractor improperly sequences the phases from the distribution equipment. The Power Company changes the phase arrangement at their transformer. Phase leads from the load side of the compressor contactor, which are improperly sequenced to the phase connections of the ESC 201. The ESC 201 will detect single-phase conditions. If one or more phase is lost the ESC 201 will drop the compressor offl ine while running. The ESC 201 will detect welded contact situations as well. This will occur if the system controller has stopped calling for a compressor to run. If the ESC 201 has two or more phase attached and a run proof the ESC 201 will alarm the phase light. The ESC 201 will turn the oil back on to prevent damage to the compressor should the compressor continue to run. This also will prevent damage to the compressor in the event that a mechanic closes the contactor manually (This should not be done under any circumstances). I. ESC 201 In General; If the ESC 201 Is Not Operating Properly Please Check The Following: Check the power supply to make sure that the ESC 201 is receiving 24 VAC control power to terminals marked A/C. Check fuses F1 and F2 to see if any of these are blown. Make sure that the ESC 201 is solidly grounded via the ground strap that is provided on the lower right hand corner of the ESC 201 when mounted horizontally. Make sure that all of the commons for the compressor safeties are connected to points A7 and B7 and it is solidly grounded. 4

6 J. Oil Flow Switch Check; The Oil Flow Switch Must Be Checked On A Regular Basis. Below You Will Find The Procedure For Checking This Item: Close the oil ball valve and wait for 15 seconds. If the ESC 201 does not take the compressor off-line the fl ow switch must be replaced. The switch could have possibly gotten debris in it and piston will not drop down to open the switch. K. AMOT Valve; If You Are Having Problems With The AMOT Valve(s) Not Functioning Properly The Compressors Will Trip On High Discharge Temperature The AMOT valve may be examined in the following manner. The valve can be disassembled for servicing. If this is done care must be taken not to damage the oil rings located inside the valve. Copper shavings could have caused the valve to jam and not mix properly. Examine the valve for shavings and remove them. Reassemble the valve. The internal element has gone bad; to check the element one of two methods is acceptable. Run hot water over the temperature-sensing element to make sure that the valve will operate. If hot water is not available then use a lighter. Hold the lighter under the temperaturesensing element for just a moment. L. Compressor Checks; The Following Will Allow For Compressors Checks For The Following Conditions: Checking a compressor that does not appear to be pumping. Shut the compressor off and close the suction service valve. Restart the compressor and see if the compressor will pull into a short vacuum. Use a gauge on the suction valve s access fi tting to check. If the compressor does not then it should be replaced. The Copeland screw compressor contains an internal check valve. The symptom of a bad check valve is when the compressor cycles off you will hear the rotors turning and close the suction service valve. Turn the compressor back on and allow the compressor to pull into a vacuum (verify with your gauges). If the compressor will not hold a vacuum then the check valve is bad. The compressor may be locked on manually until a new check valve can be installed. M. Compressor Logged With Oil; This Condition Could Occur Under The Following Conditions: The oil solenoid could stick open and fi ll the compressor with oil. To verify the problem of the oil solenoid observe the oil line sight glass. If there is movement of oil in the sight glass after the compressor has been cycled off. The compressor will not start and should trip the branch breaker due to lock rotor condition. To resolve the problem the oil line ball valve must be closed and the oil line should be pumped out. The solenoid must be taken apart and inspected. If there is debris in the valve clear it. If the internal components of the valve are bad a rebuild kit can be purchased to repair it. After the valve has been repaired the compressor must be cleared of oil. There is a drain plug on the bottom of the compressor midway between suction and discharge. Place pan underneath the compressor and remove the plug. Be sure there is no pressure in the compressor. N. General Electrical Checks; Electrical Checks Should Be Performed As Part Of the P.M. Of The System: All terminals that supply power to the compressor should be checked for tightness. These include the compressor terminals in the terminal box, contactor lugs, breaker lugs and distribution block terminals. Control points should also be checked for termination tightness to avoid false alarming of ESC 200 alarms. 5

7 O. Sub-Cooler Adjustments; The Expansion Valves Used For The Sub Cooler Must Be Adjusted To Obtain The Proper Superheat At The Economizer Inlet To The Screw Compressors: If the superheat is too high the sub-cooler liquid temperature will be higher than the system design value. This will cause the system s capacity to be lower than the design. Should the superheat at the economizer inlet be below 5 degrees the vapor entering the compressor would be too wet, when this occurs the compressor s capacity will be less than design. Additionally the compressor s amperage draw will be much higher than the running condition indicates. The superheat adjustment for the sub-cooler expansion valve must be 12 to 15 degrees at the inlet of the economizer port on the compressor. Most low temperature systems have an EPR on the economizer header to adjust the backpressure on the sub-cooler. This must be done to obtain the proper liquid temperature that is indicated in the manufacturer s legends. The EPR pressure must be set to the pressure indicated in the economizer charts, which corresponds to the liquid temperature selected by the manufacturer. The economizer chart can be found in the training manual, section labeled Economizer System & Capacity Control. P. Liquid Injection Used For Oil Cooling Medium temperature screw compressors used with R404A refrigerant can be supplied with a liquid injection system to provide oil cooling on these screw compressors. The valve, which is used for this application, is a Sporlan Y1037 valve. The valve is selected to operate when the compressor s discharge temperature reaches a range of 180 to 190 degrees. At this point the valve will open and supply liquid to the compressor via the economizer port. Should the Sporlan valve malfunction the screw compressor will draw very high amperage due to the volume of the liquid being delivered to the screw compressor. The discharge temperature will drop too low. To possible keep the compressor on line, adjust the rotolock valve to let just enough liquid in to the screw to provide some oil cooling. The indication that enough is being provided will be the discharge temperature. Check the discharge temperature to insure that 180 degrees is not exceeded. In the future, Copeland will be providing a proportional valve, which will be operated from a discharge temperature sensor that will be able to read real temperature values and operate the valve accordingly. The proportional valve will regulate the liquid feed to the compressor s economizer port. Q. Jet Kool Oil Cooling; This Is A New Development For Screw Compressor Oil Cooling Which Will Eliminate Air Cooled Oil Coolers In All Applications: The main item that can malfunction in this system is a multi position soleniod valve. The valve is controlled by discharge temperature. The valve will open or close, as the discharge temperature requires. The multi position solenoid valve is provided with a manual adjustment. The manual adjustment will allow for manual positioning of the valve. If the operator fails the mechanic can manually position the valve about ¾ of the way open. This will keep the system on-line until a new operator can be obtained. 6

8 1675 W. Campbell Road Sidney, Ohio copeland-corp.com Form No R2 Issued (11/05) Emerson Climate Technologies and the Emerson Climate Technologies logo are trademarks and service marks of Emerson Electric Co. Copeland is a registered trademark of Emerson Electric. All other trademarks are property of their respective owners. 2005, 2002 Copeland Corporation. Printed in the USA.

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