】 【Weak current College on refrigeration compressor safety protection --- Power By】 【China power house network.

<br> <br> Compressor is running, there may be some exceptions, such as: high discharge pressure, suction pressure is too low, the low oil pressure, motor overheating, excessive liquid into the cylinder. An exception, if there is no .protective measures, the compressor will be damaged. To take measures to protect the compressor can be divided into four categories: ① ② to prevent liquid hammer; pressure protection; ③ built-in motor protection; ④ temperature protection. <br> <br> .I. prevent hydraulic hammer <br> <br> When the liquid into the cylinder too much, too late, from exhaust emissions will appear in the cylinder, liquid-liquid hammer blow at very high pressure cylinder, piston, connecting rod .... and .so parts damaged; therefore, the need to adopt a series of protective measures. <br> <br> 1. fake cover <br> <br> The valve components with a spring tight pressure in the cylinder end, the formation of fake cover .. Cylinder pressure too high, the top of the exhaust valve, liquid escape, cylinder pressure rapidly reduced. <br> <br> <br> <br> Figure 13-1 with a bar pressure release valve <br> <br> Figure .13-1 fake cover for hermetic compressor. Reed valve exhaust bar-lift limiter used to release pressure spring pressure on the valve plate. Cylinder pressure rises due to hydraulic hammer, lift limiter is top, make the cylinder pressure drop. Hydraulic hammer disappears, .release pressure spring will lift limiter pressure on the valve plate, compressor continue to operate. <br> <br> 2. oil heater <br> <br> Crankcase lubricant stripping with refrigerant, ambient temperature low into increased. Compressor starting, crankcase pressure .suddenly reduced, a large number of refrigerant gas, lubricating oil is foam shaped and are caused by inhaling air cylinder, hydraulic hammer. Oil heater to heat the oil before starting, lower stripping in the amount of refrigerant in the lubricating oil is to avoid liquid .hammer of effective measures. <br> <br> <br> <br> Figure 13-2 gas-liquid separator (fluid) profile sample <br> 3. gas-liquid separator <br> <br> Figure 13-2 shows .in gas-liquid separator also known as the reservoir fluid. From the evaporator of gas-liquid mixtures in gas-liquid separator separation, gas from the upper portion of the export pipe into the outflow from the bottom. Separation of the liquid accumulated in the .bottom of the separator, where heating Gasifier liquid refrigerant into export pipe upper, cannot return the gasification of lubricating oil from the hole into the pipe and then entering the compressor. <br> <br> 2. pressure protection <br> <br> .1. suction and exhaust pressure control <br> <br> Compressor is running, the reason for the system or cause the compressor itself, there is the possibility of an exhaust pressure too high or too low suction pressure, the need to control the pressure .suction and exhaust. Common controller is not high and low pressure controller, it consists of high-voltage control part and the low voltage control parts. When the exhaust pressure exceeds a given value, high-voltage control part of the action, cut off the .compressor and the power to make it down; a value less than the given inspiratory pressure, low-voltage control part of the action, cut off the compressor power make it stop. Compressor downtime; also emit sound and light alarm signals. <br> .<br> Figure 13-3 closed type relief valve <br> <br> 2. safety valve <br> <br> To prevent refrigerant leakage to the atmosphere, take the closed valve (Figure 13-3). Valve on the side .of the disc 3 bear exhaust pressure, the underside of the bear to inspiratory pressure and spring 4 elastic. Exhaust pressure too high, the valve Disc 3 down movement, open seat lower lateral holes, high pressure gas after this side of the hole and the .valve on the lateral hole 5 flow into getter cavity. Exhaust pressure lower than the specified value, the valve Disc 3 in inspiratory pressure and spring 4 elastic effect up to close the exhaust pipe. Safety valve opening pressure regulation with the bolt 7. <br .> <br> <br> Figure 13-4 safety film <br> <br> 3. the safety film <br> <br> In suction and exhaust cavity between the security patch installed (Figure 13-4). Suction pressure difference .exceeds the specified value, the diaphragm rupture, exhaust pressure reduced. Filter diaphragm for capture breaking 6, in order to protect the compressor. <br> <br> 4. oil pressure controller <br> <br> Lubricating oil pressure differential system oil .pump outlet pressure and oil pressure in the crankcase. In order to protect the compressor good lubrication of moving parts, and that some air compressor gas control (eg hydraulic-lever control bodies) of the normal operation, you must import the voltage on the controller .and high pressure outlet is switched on. When the hydraulic pump entrance pressure difference between the too high or too low, the controller action, cut off the compressor power supply, motor stop spinning. <br> <br> <br> Figure 13 - .5 built-in temperature relays and external temperature-current relay <br> <br> 3. built-in motor protection <br> <br> 1. overheating <br> <br> Well designed and functioning of the provisions of the conditions .of the motor, the internal temperature does not exceed the permitted values, but the motor at too high or too low voltage operation, or high temperature operation, motor internal temperature exceeds allowed value, the more frequently starting, will be starting current Ambassador temperature is .too high. To motor overheating, in addition to the correct use, maintenance, installation of thermal relay. Thermal relays can be mounted on the winding (Figure 13-5a), known as a built-in temperature relays, or mounted on the motor .external (Figure 13-5b), called the external temperature-current relay. Motor internal temperature exceeds the regulation value, built-in temperature relays of bimetal blades due to deformation and make contact jumped, motor stopped. The internal temperature of the motor to .provide values for the following, contact reset circuit reconnect. <br> <br> External temperature-current relay between two terminals-shaped bimetal plate and heat exchanger. Motor currents is too large, heat exchanger for heating of bi-metal blade so that .it is in the figure a dashed line position (Figure 13-5b), contact jumped, motor stop spinning. External temperature-current relay protection motor, so it will not be excessive current and overheating. But in some situations or environments, the motor .overheating is due to excessive current, but due to the low temperature gas flows through the motor is not enough, such as: refrigeration system by plugging the amount of refrigerant circulation was small, motor cooling very poor results in internal overheating, built-in temperature .relay protection motor at this time. <b> </ b> R> <br> <br> Figure 13-6 overload relay <br> <br> 2. phase <br> <br> Three-phase motor phase will cause .the motor to start or overload. In order to protect the motor from phase of damage, using overload relay (Figure 13-6), which consists of mechanical movement and solenoid switch parts. Mechanical movement (Figure 13-6a) has four terminals, .two at the top, two in the following. Between the upper and lower Terminal 3 is equipped with a heating device. Phase, the other phase winding overload current heaters, bimetallic disc 2 heat deformation, push the pressure plate, and thus make the solenoid .switch on overload relay contact 8 (Figure 13-6b) jumped, exciting coil 7 no current, magnetic contactors are no longer closed, motor stop spinning. Overload relay also used for normal-phase motor, in the current excessive protection of motors. < .br> <br> 3. white balance <br> Interphase is not balanced voltage lead to unbalanced currents. In the current maximum temperature increase of phase, the ratio is about the square of the voltage unbalance ratio. For example: 3% voltage unbalance .generates approximately 18 per cent of the temperature rise. Protect the motor does not appear on the imbalance between phases and phase when the measures are the same. <br> <br> 4. temperature protection <br> <br> Here the temperature is .the temperature of the exhaust temperature and shell. <br> <br> 1. the exhaust temperature <br> <br> Exhaust temperature is too high results in refrigerant decomposition, the ageing of insulation materials, oil and carbon, valve damage, may .also make the capillary and drying filter clogging. Protection methods are primarily used thermostat thermostat temperature induction and exhaust should be placed near the exhaust vent, the exhaust temperature is too high, the temperature controller action, cut off the circuit. <br> <br .> If exhaust overheating caused by hot gas bypass, you should not use downtime method should be used in spray liquid cooling. <br> <br> 2. the casing temperature <br> <br> Enclosure temperature affect the life of the compressor. .Enclosure temperature is too high may cause to the condenser heat capacity, so you should check the scenery or water condenser, the water temperature is appropriate, mixed with air in the refrigeration system or other Non-Condensable Gas condensing pressure will rise in the case of .overheating; suction temperature is too high, the enclosure is easy to heat, in addition, the motor overheating overheating will also be the case. <br> <br> Avoid overheating the enclosure to protect the compressor's fundamental approach is to deal with these issues .in the enclosure temperature protector to be installed on. The most frequently used in the enclosure temperature protector that figure 3-165b shown external temperature-current protector. It is placed in the enclosure on the right place, the case temperature is too high, disc .double metal feel temperature and deformation, so that the circuit-contact jumped, compressor downtime. <br> <br> <br>.