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COP = Energy Out
Energy In
COP = Btus Out
Btus In
COP = Watts Out
Watts In
Btus divide 3.413 = Watts
Watts times 3.413 = Btus
Btus divide 3413 =
Kilowatts
Btus Out = Btus in times COP
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Bristol TS TechnologyBristol TS Technology
Twin-Single 2 Stage CompressorTwin-Single 2 Stage Compressor
http://ts.bristolcompressors.com/tstour.html
http://ts.bristolcompressors.com/cts.html
http://ts.bristolcompressors.com/tstour.htmlhttp://ts.bristolcompressors.com/cts.htmlhttp://ts.bristolcompressors.com/cts.htmlhttp://ts.bristolcompressors.com/cts.htmlhttp://ts.bristolcompressors.com/tstour.html7/31/2019 Capacity Control Block 3
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Oil return is a major issue in variable capacity multiple evaporator systems. Current
technologies use an oil separator and/or complicated oil return cycle to ensure oilreturn after some period of operation. The Digital Scroll is a unique compressor it
does not require an oil separator or an oil return cycle.
There are 2 factors that make the oil return easy. First, the oil leaves the compressor
only during the loaded cycle. So at low capacities, very little oil leaves the
compressor. Second, as explained before, the compressor operates at full capacityduring the loaded cycle. The gas velocity in the loaded cycle is sufficient to return oil
back to the compressor. Our testing has shown that oil is able to return back to the
compressor even in the worst operating conditions low modulation, 100 meter pipe
length and 30 meter elevation (with standard oil traps), both straight and reverse
elevation.
http://www.digitalscroll.com/sb300/portal/home/normal/17/show/0/2?
Variable Capacity Oil Return
http://www.digitalscroll.com/sb300/portal/home/normal/17/show/0/http://www.digitalscroll.com/sb300/portal/home/normal/17/show/0/7/31/2019 Capacity Control Block 3
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Ultra Tech ScrollUltra Tech Scroll
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Copeland Ultra-Tech
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A piston is fixed to the top scroll to ensure that when the piston moves up, the top scroll also moves up.
There is a modulation chamber at the top of the piston that is connected to the discharge pressure
through a bleed hole of diameter 0.6 mm. An external solenoid valve connects the modulation chamber
with the suction side pressure. When the solenoid valve is in the normally closed position, the pressureon either side of the piston is discharge pressure and a spring force ensures that the two scrolls are
loaded together. When the solenoid valve is energized, the discharge gas in the modulation chamber is
relieved to the low pressure. This causes the piston to move up and consequently the top scroll also
moves up. This action separates the scrolls and results in no mass flow through the scrolls. De-
energizing the external solenoid valve again loads the compressor fully and the compression is
resumed. It should be noted that the movement of the top scroll is very small - 1.0 mm and consequently
the amount of high-pressure gas that is bled from the high side to the low side is very little.
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Copeland Semi-Hermetic Screw CompressorCopeland Semi-Hermetic Screw Compressor
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http://www.emersonclimatecontractor.com/products/air-conditioning/astp.shtm
http://www.emersonclimatecontractor.com/products/air-conditioning/astp.shtmhttp://www.emersonclimatecontractor.com/products/air-conditioning/astp.shtm7/31/2019 Capacity Control Block 3
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Three PhaseThree Phase
Voltage MonitorVoltage Monitor
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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 average measured current deviates more than
15% from published values,
a faulty compressor may be indicated.
A current imbalance exceeding 15% of the average on the
three phases may indicate a voltage imbalance
and should be investigated further.
A more comprehensive troubleshooting sequence for
compressors and systems can be found in Section H of the
Copeland Electrical Handbook.
IDENTIFYING COMPRESSOR MECHANICAL FAILURES
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Most compressors fail due to system malfunctions which must be corrected to
prevent repeat failures. After a compressor fails, field examination of the failed
compressor often will reveal symptoms of system problems.
Proper corrections will help eliminate future failures.
REFRIGERANT FLOODBACK
This is a result of liquid refrigerant returning to the compressorduring the running
cycle. The oil is diluted with refrigerant to the point it cannot properly lubricate the load
bearing surfaces. The liquid washed the oil off the pistons and cylinders during the
suction stroke causing them to wear during the compression stroke. The liquid dilutesthe oil in the crankcase and the refrigerant rich oil will be pumped to the rods and the
bearings through the crankshaft. As the refrigerant boils off, there will not be enough oil
for sufficient lubrication at the bearings farthest from the oil pump. The center and rear
bearings may seize or may wear enough to allow the rotor to drop and drag on the stator
causing it to short.
Correction: (1) Maintain proper evaporator and compressor superheat.(2) Correct abnormally low load conditions.
(3) Install accumulators to stop uncontrolled liquid return.
IDENTIFYING COMPRESSOR MECHANICAL FAILURES
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FLOODED STARTS
This is the result of refrigerant vapor migrating to the crankcase oil during
the off cycle. When the compressor starts, the diluted oil cannot properly
lubricate the crankshaft load bearing surface causing an erratic wear or
seizure pattern.
Correction: (1) Locate compressor in warm ambient or install continuous pump
down.
(2) Check crankcase heater operation.
SLUGGING
This is the result of trying to compress liquid refrigerant and/or oil, in the cylinders.
Slugging is an extreme floodback in air cooled compressors and a severe flooded
start on refrigerant cooled compressors.
Correction: (1) Maintain proper evaporator and compressor superheat.
(2) Correct abnormally low load conditions.(3) Install accumulators to stop uncontrolled liquid return.
(4) Locate compressor in warm ambient or install continuous pump down.
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R-717 SystemR-717 System
Corrosion FailureCorrosion Failure