2 minute read
Pump Control
Controlling and monitoring pumping systems for best performance
Good pump selection is based on achieving the Best Efficiency Point (BEP); however, to truly get the best from a pumping system, it needs to be continually monitored and controlled effectively. T-T Controls, a division of T-T Pumps, outlines the benefits of this approach.
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The days of just having an isolator on the wall, with a pump operating flat out when there is little or no demand, are gone, as energy is too valuable a commodity to waste.
Operational performance, therefore, needs to be both monitored and controlled effectively to meet the needs of the system or process whilst giving maximum efficiency at all times.
Even the most basic of motor starters today will offer some form of pump protection from short circuit via fuses or MCB’s, or overload protection either by a thermal relay or thermistor device. However, these offer very little indication of the demands of the system, and at best would only offer system monitoring in the form of simplistic volt free contacts for use with building management systems (BMS).
With the various solutions available today for collecting, storing and transmitting data, what is required for truly efficient control is a technically advanced intelligent remote monitored control system, overseeing several elements seamlessly in real-time.
Variables such as pressure, flow rate, rate of change in level and the current consumption a motor, can all be logged to get a full understanding of both instantaneous demand and to build up a database of historical information.
Instantaneous data, for example pressure drop, can be evaluated and processed via the use of a PID (proportional integral derivative) control loop. This approach looks at congruent variables and determines the rate of change in these values to regulate and fine-tune operational control. An example of this would be evaluating pressure drop in a system to establish whether a pump needs to operate fully using maximum energy, or whether it can use less energy by operating at a lower frequency with the use of a Variable Speed Drive.
The same PID control philosophy could also be applied to temperature variations on closed-loop heating systems, or heat recovery applications, or inversely, chilling and temperature reduction systems and other systems where continuous modulating control is required.
Stored historical data monitoring enables comparisons to be made on specific maintenance indicators, such as bearing temperature or vibration monitoring which can prevent costly breakdowns. Additionally, real-time analysis of multiple factors such as wet well level, motor current consumption, power supply, and voltages can all indicate if a pump motor is running beyond its Best Efficiency Point.
The use of remotely monitored data collectedon a day-by-day, hour-byhour, minute-by-minute basis, gives a true indication of how a pump is used, and in the case of a pumping station shows how the wet well system is used 365 days per year by residents on a housing development.
This valuable insight can be used to schedule service visits and assess the urgency required to attend breakdown visits, with data used to determine any underlying issue in the system.
In the ever-changing world where access restrictions and physical site visits are becoming more problematic, the reliance on, and need for, remote monitoring and intelligent control is more prevalent than ever. The starter on the wall will eventually become a thing of the past.
