Control panel products enhance smooth operations.
Operating reliable, efficient lift stations can be challenging. End-users with a lean staff maintain hundreds of remote stations in a wastewater system, which are often located in difficult-to-access or hazardous areas. This makes maintenance and troubleshooting time intensive.
Maintenance is a critical consideration when control panels and components are subjected to extreme weather conditions and caustic liquids and gases. Unforeseen or extended downtime can be caused by many issues: pump ragging and overheating, broken impellers and malfunctioning level sensors. Environmental hazardsand hefty fines can result from lift station downtime.
Advanced Overload Relays
By monitoring energy and power factor, facilities can avoid peak demand charges, shed non-vital loads, identify and correct increased consumption, spot the discrepancy between equal loads and see power factor line items.
Advanced overload relays can monitor current and voltage in each phase and identify conditions that can lead to motor or pump failure with greater speed, reliability and repeatability than traditional failure detection devices. With remote, real-time data monitoring, facilities are able to protect assets, prevent energy waste and manage costs—all while maintaining system integrity and uptime.
Facilities can monitor volts, amps, thermal capacity, frequency, power, power factor and easily translate this data to motor or pump conditions.
Overload relays allow identification of unusual and inefficient operations in real time. They can monitor energy use to avoid peak demand charges, shed non-vital loads and detect increased energy consumption, discrepancy between equal loads and power factor line items. With industry standard communication protocols and central supervisory control and data acquisition (SCADA) systems, customers can identify and correct situations to prevent downtime before incurring energy costs. Through fieldbus commands and online via the operator interface (OI), customers can remotely monitor and control their systems and shutdown nonessential assets. Energy use between similarly-sized pumps can be compared and spot checks can be eliminated. When maintenance is necessary, remote lift station operators can dispatch personnel. Neglected conditions can be remedied as they occur. Without the ability to detect and fault when low-power conditions occur, pumps can heat up, damaging the seal, and failing the pump.
Without an overload relay that detects low power, the pump would continue to run. The water level would not increase and the float switch would not drop. A second pump may be turned on to compensate. Two pumps would be running and doing the work of a single pump. The protective-fault, low-power feature of today's overload relays can help avoid needless run-time hours and component wear would be reduced.
VFDs and Soft Starters
Today's sophisticated variable frequency drives (VFDs) are better able to fine-tune motor speed to regulate and control flow, resulting in energy savings from 10 to 50 percent. Soft start controllers reduce motor demands during startup, resulting in reduced energy and increased mechanical system life.
The latest VFDs are more accurate and energy efficient. Enhancements in capacitors, direct current (DC) link reactors, insulated gate bipolar transistors (IGBTs), heat management, processing power and measuring technology and new algorithms are improving drives' efficiency to levels greater than 97 percent.
Soft start controllers provide smooth acceleration and deceleration of the load, minimizing shock to mechanical components, extending the life of the system, increasing reliability, reducing downtime and lowering costs. Soft starters reduce slippage, squealing and the stretching of belts. With special pump control algorithms, the soft starter can control motor deceleration, reducing the water hammer effect. A compact soft starter provides the same benefits of soft starting without the need for a change in enclosure sizes or additional assemblies. High Performance soft starters have extensive monitoring and protection functionality, improving troubleshooting.
Using a drive with a soft starter built into the bypass provides enhanced control, flexibility and protection. Adding a soft starter to the bypass allows the motor to be ramped up to full speed when in the bypass, reducing the mechanical and electrical stress on the system.
Sophisticated Controls and Interfaces
Today's innovative and small programmable logical controllers (PLCs) monitor diverse parameters in remote lift stations to reduce maintenance and improve efficiency. OIs help operators visualize equipment activities, monitor and control equipment, provide real-time and historical trending, alarms, database interface and the ability to run soft logic and make decisions. . PLCs monitor the moisture level and temperature and the operation of the pump to help optimize maintenance schedules and prevent downtime. Rugged OIs and human machine interfaces (HMIs) help monitor processes and keep them running.
PLCs are also able to share information with operators remotely so that maintenance personnel offsite know if an unexpected event has occurred. In larger systems, they can help facilitate load sharing so that the operational hours can be balanced between pumps to extend equipment life.
Sophisticated OIs offer lift station operators connectivity with ruggedized electronics for increased reliability in harsh environments.. High performance interfaces feature increased memory to run larger applications, store event histories and record operational trends. They also have enhanced display brightness and resolution and faster application performance and allow operators to move easily among machines and provide easy access to PLCs and other devices. Some interfaces can combine the functionality and flexibility of Microsoft® products with the reliability of solid-state hardware design, providing protection for the operating system and software.
Economic Control Discrete Processes
Relays provide the following:
- Voltage and current monitoring relays facilitate correct operation of the pump.
- Alternating relays share the load automatically between two pumps.
- Timing relays provide additional functionality during the pumps' running time and start-up.
- Definite purpose relays accomplish tasks such as isolating one voltage level or energizing a starter.
Pushbuttons
Global suppliers provide customers with comprehensive 22.5 millimeter and 30.5 millimeter pushbuttons to meet diverse needs. Remote lift station controls include flush and extended pushbuttons, along with selector switches, pilot lights and emergency stops.
E-stops are the red operator buttons that users hit in the case of emergency, to protect personnel and equipment. These need to meet EN 418 IEC 609475-5, which does not allow for ‘teasing' the contact block, but requires trigger action.
Molded Case Circuit Breakers
Molded case circuit breakers (MCCB) are designed to provide circuit protection for low-voltage distribution systems and protection against overloads in conductors and short circuits in connected equipment. Some manufacturers offer MCCBs that are 99.99 percent reliable
Panel boards use either fuses or breakers. Circuit breakers offer enhanced safety, improved reliability and energy savings. Compared to fuses, circuit breakers save energy with less watt loss for similar ratings. Circuit breakers can be reset after they trip, while fuses must be replaced and can be remotely reset.
In a remote lift station, a Walking Beam Solution can be useful. It prevents the main and emergency from being “on” at the same time.
Pumps & Systems, October 2010