Challenge

The instrumentation department of a major sugar producer in Colombia was having recurring issues with the mechanical switches that were installed on the centrifuges:

1. The switches were occasionally subjected to pressure spikes on the centrifuges which damaged the sensors.
2. Mechanical pressure gauges were unable to store any process information including magnitude and frequency of the pressure spikes.
3. After overpressure situations, the operators could not determine if the mechanical switches were functioning properly as the devices were unable to report their health.

Solution

The mechanical switches on the centrifuges were replaced with UE’s Excela electronic switches. Each Excela switch was installed along the centrifuge’s water injector line to ensure that the water was injected into the drum at 90 psi. When the pressure falls below the 90 psi setpoint, the Excela shutdowns the centrifuge system via the programmable logic controller (PLC). The centrifuge is reactivated once the water pressure is restored.

Excela installed on a water injector line of a centrifuge (left) and Individual centrifuge with the Excela (circled) (right)

The Excela was selected for the following reasons:

1. The Excela provides the customer with operational visibility with its embedded device diagnostics. It informs the operator that it is functioning properly (health diagnostics through the LCD display), as well as basic process statistics (trip point counter, max/min process values).
2. Excela’s large display allows for easy pressure reading and local programming of setpoints and deadband.
3. The Excela is more affordable than transmitters. The Excela electronic switch can also be wired directly to the 24VDC PLC system with existing wiring infrastructure, saving installation cost.