What is meant by surging in compressor?
Compressor surge is a form of aerodynamic instability in axial compressors or centrifugal compressors. The term describes violent air flow oscillating in the axial direction of a compressor, which indicates the axial component of fluid velocity varies periodically and may even become negative.
What causes compressor surging?
Surge is a condition that occurs in compressors when the amount of gas they are trying to compress is insufficient for the size of the compressor and the blades lose their ability to transfer energy from the shaft to the fluid, causing a reverse flow of the gas.
What is Surge test in compressor?
A compressor undergoes surge testing to optimize the calibration of anti-surge control systems so that they fully protect a compressor from potentially damaging surge conditions while maximizing the compressor’s turndown (operating range).
How we can reduce surging in a compressor?
Surge can be prevented by providing an anti-surge valve, which allows more flow to be recycled back to the suction side and enables moving the compressor operating point away from the surge line.
What is surge and choke in compressor?
Surge is a violent flow reversal that occurs when the process restricts the compressor flow below a certain minimum value. Choke occurs when the process does not create enough restriction to the compressor flow and the compressor operates at its maximum flow for a given performance level.
What is stalling and surging?
In elementary terms, stall is a disturbance of the flow in the tangential direction, while surge is a disturbance in the axial direction. During stalled operation, the average flow rate through the compressor is steady, but during surge, the flow rate will pulse—sometimes so violently that reversed flow is induced.
What is Surge test?
Surge voltage testing is used to discover insulation problems in wound materials. In studies, experts have determined that 60% of motor failures start out as coil shorts within a winding. A surge voltage test is the only testing method which can determine insulation problems in wound materials.
What is surging in compressor and how it can be prevented?
Surge is a dynamic instability that occurs in turbo-compressors. As the flow through a compressor is reduced, a point is reached where the flow pattern becomes unstable. Surge happens quickly, and conventional instruments usually fail to recognize the effects of surge.
What is surge margin in compressor?
The surge margin (SM) is defined as the distance between the surge line and the operating point on a vertical line for a constant corrected mass flow value. Several definitions are in use to define the SM. From the compressor map it is clear that the distance to the surge line can be defined using multiple definitions.
How do you control a surge?
Methods for controlling hydraulic surges include utilizing a gas-loaded surge relief valve, spring-loaded pressure safety valves, pilot-operated valves, surge suppressors, and rupture disks.
Why do you need a surge test?
Surge tests are critical because they are the only test that finds turn-to-turn insulation weaknesses. These weaknesses start at voltages above the operating voltage of the motor and are precursors to serious failures and shutdown of a motor.
What is motor surge?
Education & Training @ Motor Diagnostic Systems. Overview. Surge testing is a technique to test the dielectric strength of the insulation in windings. These windings can be solenoids, toroids, transformers, or some other type of winding like those found in electric motors.
What is a surge point?
At some point on the compressors operating curve, there exists a condition of minimum flow/maximum head where the developed head is insufficient to overcome the system resistance. This is the “surge point.” When the compressor reaches this point, the gas in the discharge piping back-flows into the compressors.
What is surging and choking in compressor?
What is surge limit in compressor?
Surge is defined as the operating point at which centrifugal compressor peak head capability and minimum flow limits are reached.
What is compressor surge margin?
What causes a surge?
There are several causes for a power surge. The main reasons are electrical overload, faulty wiring, lightning strikes, and the restoration of power after a power outage or blackout.
How do you perform a surge test?
How is Surge Testing Performed? The test can be performed on the motor winding without actually connecting to the motor itself. The test equipment can be connected to the load side of the motor starter. During the test a voltage pulse is placed across two of the three windings while the third is grounded.
How do you test a surge?
What is surging and stalling?
What is the difference between a surge and a spike?
If more voltage is introduced than an electrical appliance is designed to handle, this is called a power surge or transient voltage. Any such voltage increase that lasts at least three nanoseconds is considered a surge. If the increase is only present for one or two nanosecond, that’s called a power spike.
What is the purpose of surge test?
A surge test is the only test that finds weak turn-to-turn insulation. This is due to higher voltages used in a surge test. Low voltage tests do not stress the insulation and consequently dielectric weaknesses are not found. A surge test is the only test that finds weak coil-to-coil and phase-to-phase insulation.