Motor monitoring

There always is a relation between fuel composition and that of hydrocarbon emissions to the atmosphere, whether it concerns hydrocarbon emissions from evaporative losses from the fuel system, or from exhaust gases. This is the reason that environmental protection regulations include monitoring the composition of motor and heating fuels. We will describe here the regulations already in existence and the work currently underway in this area with its possible effects on refining. 

The principle of operation of the hydraulic reciprocating pump is similar to the beam pump, with a piston-like sub-surface pump action. The energy to drive the pump, however, is delivered through a hydraulic medium, the power fluid, commonly oil or water. The power fluid drives a downhole hydraulic motor which in turn drives the pump. A separate surface pump delivers the hydraulic power. The power fluid system can be of the closed loop or of the open type. In the latter case, the power fluids are mixed with the produced fluid stream. The performance of the hydraulic pump is primarily monitored by measuring the discharge pressures of both surface and sub-surface pumps. 

When this quantity is required to monitor the health of a machine, say, for its protection, it can be substituted by k where is the equivalent maximum current at which the motor can operate continuously. It may also be considered as the current setting of the relay up to which the relay must remain inoperative. 

With different approaches to monitor and control the basic parameters of the motor, i.c. 4, /, and sin 6, many tnorc alternatives arc possible to achieve the required speed variation in an a.c. machine. Control of these parameters by the use of an encoder can provide an accuracy in speed control as good as a d.c. machine and even better. 

With this technology it is now possible to achieve extremely accurate speed control of the order of 0.01 % to 0.001 %. To achieve such high accuracy in speed control, closed-loop feedback control systems and microprocessor-based control logistics can be introduced into the inverter control scheme to sense, monitor and control the variable parameters of the motor to very precise limits. 

These rolls are driven by motors and /W, whose speed is controlled through the tension of the travelling sheet. The tension of the sheet is adjusted by monitoring the diminishing diameter of the payoff roll and the thickness of the sheet. 

With the help of bridle no. I driven by motors M and M4, the uncoiler section speed is controlled by monitoring the tension of the travelling sheet and hence maintaining constant speed of the sheet in the uncoiler section. The tensile difference of T tind Ti determines the speed of the uncoiler. Speed and tension of the sheet must remain constant for absolute synchronization between the uncoiler process and the recoiler sections. 

Before the finished sheet is finally cut into lengths as required or rolled into recoilers its exit speed and tension is monitored and controlled again by bridle no. 4, driven by motors M15 and... 

In all the above conditions, the rotor would heatup much more rapidly than the stator due to its low thermal time constant (t), and its smaller volume compared to that of the stator, on the one hand, and high-frequency eddy current losses at high slips, due to the skin effect, on the other. True motor protection will therefore require separate protection of the rotor. Since it is not possible to monitor the rotor s temperature, its protection is provided through the stator only. Separate protection is therefore recommended through the stator against these conditions for large LT and all HT motors. 

Solid-state microprocessor based these are more sensitive and accurate. They can be made digital to be connected to a computer for remote monitoring and control of the process that the motor is driving. 

To warn of an unfavourable operating condition by the use of an audio-visual alarm or trip or both, schemes can be introduced in the control circuit by means of a temperature detector or other devices to monitor any or all of the following internal conditions of a motor ... 

To detect the above, sensing and monitoring devices can be installed in the motor. Some of these are built-in during the manufacturing stage and others are fitted at site during installation. 

Several types of sensing and monitoring devices are available that are embedded at a motor s vulnerable locations and the hot spots at the manufacturing stage... 

HT motors specifically, and large LT motors generally, are recommended to have six such detectors, two in each phase to sense or monitor the temperature of likely hot... 

Since it is not practical to manufacture a llameproof enclosure due to its size and bulk and the number of knockouts and openings on the doors for switches, metering, indicators, and pushbuttons (PBs) etc., it is common practice to locate the.se assemblies some distance from the affected area in a separate well-ventilated room. Depending upon the location and intensity ol contamination, it may be permissible to meet the requirement by using a pressurized enclosure by maintaining a positive pressure inside the enclosure similar to that for motors (Section 7.1.3..3). When there arc many switchgear assemblies, the room itself can be pressurized, which is safer and easier. Small enclosures, however, such as a PB station, switch or a switch fuse unit or an individual starter unit etc., which can be easily made of MS plates or cast iron, as discussed in Section 7.13, can be mounted in the hazardous area while the main MCC can be installed in the control room, away from the contaminated area and from where the process can be monitored. 

For loads, such as on motors where the capacitor unit is being switched with the machine, or where close monitoring of the capacitor health is a prerequisite to avoid an eventual outage of the capacitor unit by gradual depletion of its capacitance, internally protected capacitor units may be preferred. 

---