【Mechanical Equipment Technology Edition】Daily Question 20180102: Common Faults in Refrigeration Systems (4.3)
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This post was last edited by YORK Industrial Refrigeration on 2018-1-6 at 09:07. Starting from now, in order to enhance communication among members, a 【Daily Question】 activity has been launched on the Mechanical Equipment Technology forum. We hope everyone will participate actively to progress and improve together! ! ! Rewards: 3 wealth points for active participation, 10-15 wealth points for correct answers. This question is valid for two days; no score will be assigned after that period. What are the reasons why the load cannot be increased in a screw refrigeration compressor? What’s the reason why it can’t be uninstalled? Answer: There’s little to say about the reasons related to solenoid valves; blockages in the oil circuit are rare, and it’s uncommon for the oil piston seals to get stuck inside the piston chamber. In most cases, it’s the slide valve that gets stuck. https://attach01.hcbbs.com/forum/201712/27/083237nbgb4v9n7dbhbd9b.gif =============================== Premium promotions: Mechanical equipment——Summary of work done by equipment managers in 2017 https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1881872 Mechanical equipment——Maintenance procedures for York screw compressors https://bbs.hcbbs.com/thread-1806833-1-1.html Mechanical equipment——Upgrades to York Quontum control centers https://bbs.hcbbs.com/thread-1804837-1-1.html Mechanical equipment——Major repairs of GEA Grasox screw compressors https://bbs.hcbbs.com/thread-1800467-1-1.html Mechanical equipment——Disassembly and maintenance of British HOWDEN screw compressors https://bbs.hcbbs.com/thread-1832529-1-1.html Mechanical equipment——Disassembly and maintenance of Japanese MYCOM screw compressors https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=
1. Reasons why the compressor does not load: The ambient temperature is too low, and the viscosity of the lubricating oil is too high； Capillary obstruction ； There are problems with the pressure regulation system, such as blocked pipes and stuck valves ； Oil filter clogged ； 2. Reasons why the compressor does not unload: Issues with the capacity control system, such as solenoid valve failures ； Oil circuit system issues, such as insufficient lubricant level ； Control system issues, such as damaged temperature control components ；
Generally speaking, when a screw compressor is loaded or unloaded, its exhaust volume is adjusted, thereby changing the compressor’s cooling capacity; the cooling capacity of the compressor is adjusted according to different load requirements. It is set based on the compressor’s control circuit; once the program is set, it adjusts automatically. If there are issues with loading or unloading, check whether the solenoid valve is faulty.
I. The compressor of the screw chiller unit cannot be loaded: The operating conditions of the screw chiller unit are outside the specified range; the oil temperature is too low while the density is too high. Blockages in components such as the capillary tube, oil filter, and oil circuits, damage or malfunction of the energy control solenoid valve, problems with the control system related to the solenoid valve, damaged sealing gaskets on the base of the energy control solenoid valve, or errors in its use or installation, as well as damage to the control valve and the piston of the oil cylinder, can all cause damage to the screw-type chiller unit or prevent it from starting properly. II. The screw unit cannot be unloaded: The energy control solenoid valve is damaged or not functioning properly. There is a problem with the solenoid valve control system. For the SRC-S system, which features a refrigeration screw chiller with energy regulation, the sealing gaskets under the flange covers are installed incorrectly; the sealing surface of the cylinder piston is damaged, and the connecting rod of the piston cylinder is broken. The insulation of the motor has been damaged, and there is moisture inside the motor windings. The motor of the screw chiller will not start. Due to the requirement for cooling capacity, the protection device has activated, and during startup the compressor operates at full load, resulting in too low exhaust pressure and voltage levels.
1. Reasons why the compressor does not load: The ambient temperature is too low, and the viscosity of the lubricating oil is too high； Capillary obstruction ； There are problems with the pressure regulation system, such as blocked pipes and stuck valves ； Oil filter clogged ； 2. Reasons why the compressor does not unload: Issues with the capacity control system, such as solenoid valve failures ； Oil circuit system issues, such as insufficient lubricant level ； Control system issues, such as damaged temperature control components
The screw unit cannot be loaded or unloaded: The energy control solenoid valve is damaged or not functioning properly. There is a problem with the solenoid valve control system. For the SRC-S system, which features a refrigeration screw chiller with energy regulation, the sealing gaskets under the flange covers are installed incorrectly; the sealing layer on the piston of the oil cylinder is damaged, and the connecting rod of the piston cylinder is broken. The insulation of the motor has been damaged, and there is moisture inside the motor windings. The motor of the screw chiller will not start. Since cooling capacity is required, the protection device has activated. During startup, the compressor operates at full load, and the exhaust pressure is too low along with abnormally low voltage levels