Pumps, heaters, and other monitoring applications

Current sensors are commonly used to prevent pump blockages and suction losses. In wastewater applications, organic matter can clog pumps and damage motors and pumps before thermal overload trips. Alternatively, blockages in the pump suction line can cause the pump to run idle, overheat, and damage the seals. Install a current sensor on one leg of the motor wire so that the operator can monitor overload and underload conditions and take corrective measures before the equipment is damaged.

Use the same technology to monitor equipment that supplies heat to finished products, storage systems, or recycled materials. If the heater malfunctions, the batch or process may have to be scrapped. By integrating the current switch signal with the automation system, the operator can monitor the on/off status, issue fault alarms, or automatically turn on the backup heater.

New Trends in Current Switch/Relay Technology

There are two new trends emerging in the current switch/relay market. Nowadays, smaller control panels and crowded switchgear are driving the demand for more compact devices with higher ratings and more universal installation options.

Relays are typically used to start loads, while pressure switches or zero speed switches are used to monitor loads. This method requires two installations and multiple conduit runs, which increases the complexity of the system. Nowadays, modular relays can be quickly connected to various current sensors, from adjustable set point current switches to integrated sensors. This modular approach allows operators to turn on the motor, alarm the on/off status, and monitor the load condition of the motor through a single installed device.

The second trend is towards the development of more intelligent relays. The new current sensor based on microprocessors will automatically perform self calibration during initial startup. Other smart devices have user programmable timers that can compensate for short-term anomalies and motor start-up surges. These enhanced control capabilities, higher ratings, and solid-state reliability have led to the widespread acceptance of current sensing technology as a replacement for traditional instruments.