Detection of reverse rotation or operation of a refrigerant compressor is provided. In one aspect, a detection technique includes starting the compressor and determining the compressor is rotating in a reverse direction if a dome temperature of the compressor fails to exceed a first predetermined threshold at or before expiration of a first predetermined period of time following starting, the refrigerant pressure at a refrigerant inlet of the compressor remains constant for a second predetermined period of time following starting, and/or the frequency of pressure oscillations of the refrigerant at the refrigerant inlet exceeds a second predetermined threshold. Another technique for determining the compressor is rotating in the reverse direction involves analyzing a waveform associated with motor current, motor torque, or refrigerant pressure. Further embodiments, forms, features, and aspects shall become apparent from the description and drawings.

A method of operating a vacuum pump system, the method including the steps of: operating a primary vacuum pump having a variable speed motor; connecting at least two secondary vacuum pumps in parallel with said primary vacuum pump; dividing the secondary vacuum pumps in groups, each group including at least one secondary vacuum pump; and assigning a priority for each of said groups. The method further includes the steps of measuring the inlet pressure p1, comparing the measured inlet pressure p1 with a predetermined pressure value p0, and if p1 is higher than p0, starting the secondary vacuum pump at a first predetermined startup load S.sub.startup,1 if it includes a fixed speed motor, and/or starting the secondary vacuum pump at a second predetermined startup load S.sub.startup,2, if it includes a variable speed motor.

There is disclosed a pump apparatus which can more accurately determine the occurrence of an abnormal vibration. The pump apparatus includes: a pump; an electric motor for driving the pump; an inverter as a speed changing means for the electric motor; a vibration detector for detecting at least one of a vibration of the pump, a vibration of the electric motor and a vibration of the inverter; and a controller for controlling the pump. The controller includes a storage unit for storing a measured vibration value measured by the vibration detector. The storage unit has a storage table which, when the rotational speed of the pump is increased stepwise to a predetermined rotational speed, stores the measured vibration value measured at each step.

A pumping installation includes at least one first positive-displacement machine and one second positive-displacement machine, as well as a control module, in which installation a gas is evacuated from an enclosed volume by means of the first positive-displacement machine and/or the second positive-displacement machine. The pumping installation includes at least one control valve controlled by the control module and a pressure sensor for sensing the value of the pressure at the outlet of the first positive-displacement machine and/or a temperature sensor for sensing the value of the temperature at the outlet of the first positive-displacement machine in order to control the flow of gas between the enclosed volume and the outlet of the pumping installation.

The invention relates to a method for controlling a rotary screw compressor, having at least a first and a second air-end, wherein both air-ends are driven separately from one another and speed controlled. According to the invention, the following steps are carried out: detection of a volume flow taken at the outlet of the second air-end; adjustment of the rotational speed of both air-ends, when the removed volume flow fluctuates in a range between a maximum value and a minimum value; opening of a pressure-relief valve, if the volume flow falls below the minimum value; and reduction of the rotational speed of at least the first air-end to a predetermined idling speed (V1.sub.L) to reduce the volumetric flow delivered by the first to the second air-end.

A vacuum pumping system includes a plurality of positive displacement vacuum pumps, and more particularly a plurality of positive displacement vacuum pumps working in parallel. The vacuum pumping system includes a management unit that carries out a synchronized control of all the positive displacement vacuum pumps of the vacuum pumping system and thus allows to check possible risk of contamination of the vacuum pumping system and carry out, if needed, the necessary corrective actions without requiring any modification to the construction of the vacuum pumping system.

A power saving vacuuming pump system is based on complete-bearing-sealing and dry-large-pressure-difference root vacuuming root pumps includes an input valve at an input end of a vacuum space for receiving gas mixture of saturation water vapor and non-condensed air from a condenser of a power plant; a first root vacuum pump connected to the input valve for receiving gas mixture from the input valve and then compressing the gas mixture; a second root vacuum pump connected to the first root vacuum pump for receiving gas mixture from the first root vacuum pump and then compressing the gas mixture. Inner connection walls between the vacuum chamber and the two bearing rooms are installed respective bearings which are installed to be around the driving shaft, and thus all the vacuum chamber and the two bearing rooms are tightly sealed. The vacuum chamber is completely dried so as to prevent from internal emulsion.

A progressive cavity pump (PCP) system includes a PCP with a rotor rotatably disposed in a stator, a permanent magnet motor, sucker rod(s), and a control system. The rotor is coupled to one of the sucker rods via a high-torque connection that allows for counter clockwise rotation without loosening the connection between the rotor and sucker rod. The control system operates the system in a production mode by rotating the rotor clockwise. Upon manual input by a user, or automatic triggering when protections settings of the control system call for a shutdown or cleanout or when the control system senses an imminent pump shutdown, the control system operates the system in a reverse mode by rotating the rotor counterclockwise. The reverse mode pumps fluids and suspended solid particles down into the well prior to pump shutdown to inhibit the solids from clogging the pump or preventing the pump from restarting.

An eccentric screw pump hasa pump housing having a pump inlet opening and a pump outlet opening, a stator disposed in the pump housing, a rotor disposed in the stator, a drive unit comprising a drive motor and a driveshaft which for transmitting a torque connects the drive motor to the rotor, wherein the rotor for a rotating movement about a rotating axle is guided in the stator, a state sensor for detecting a state variable of the eccentric screw pump, where the state sensor, for detecting a state variable on the rotor or on the driveshaft, is disposed on the rotor or the driveshaft, or is connected to the rotor or the driveshaft by means of a signal line and is disposed so as to be spaced apart from the rotor or the driveshaft.

Provided are a compressor and a monitoring system that can specify a cause of an anomaly of a sensed value of a sensor. A compressor (1) includes: a temperature sensor (11A) that senses a temperature of a compressed air on a discharge side of a low-pressure-stage compressor body (3) and on an upstream side of an intercooler (5); a pressure sensor (12A) that senses a pressure of the compressed air on the discharge side of the low-pressure-stage compressor body (3); a temperature sensor (11B) that senses a temperature of the compressed air on an intake side of a high-pressure-stage compressor body (6) and on a downstream side of the intercooler (5); a temperature sensor (11C) that senses a temperature of the compressed air on a discharge side of the high-pressure-stage compressor body (6); a controller (8) that decides whether or not an anomaly has occurred in sensed values of the sensors (11A), (11B), (11C), and (12A), and estimates a cause of the anomaly; and a display device (9) that displays the cause of the anomaly estimated by the controller (8).