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Alarm Trip 1-out-of-2 Voting with High Availability

Alarm Trip 1-out-of-2 Voting with High Availability
A customer has a Safety Instrumented Function they need to implement with two independent level transmitters (radar), each wired to a separate STA Functional Safety Trip Alarm. The process will trip if either level reaches the set point, for example a 1 out of 2 (1oo2) voting. However, if the alarm trip (STA) detects an input or unit fault. The customer did not want the process to trip. Instead they wanted to take the faulty unit out of service leaving the process running with the one good level and alarm trip. 
Published: November 28, 2017

Sharing Process Variables: Quad Isolator

Sharing Process Variables: Quad Isolator

Problem: When sharing a Process Variable (PV) with multiple systems, the connection needs to be thought out carefully. Sending a signal go to more than one PLC needs to be well thought out just as carefully.

Published: November 7, 2017

Heater Differential Temperature Monitoring and Alarming Using Associated IS

Heater Differential Temperature Monitoring and Alarming Using Associated IS

Challenge: Measure inlet and outlet temperature of a process heater using existing three-wire RTDs and provide a 4-20mA process variable signal, representing the differential temperature across the heater, to a local alarm trip for heater protection and share that differential temperature signal with the Basic Process Control System (BPCS). The measurements are in a hazardous area and plant standards require the use of a certified IS system.

Published: October 23, 2017

Alumina Refinery: Overpressure Protection of a Filter Vessel

Mining & Metal Refining Industry

Alumina Refinery: Overpressure Protection of a Filter Vessel
The process of converting bauxite to alumina for aluminium metal refining involves a complex manufacturing process.  Much of this process requires critical temperature and pressure control, which if left unchecked could result in catastrophic consequences. Learn how Moore Industries solved this problem for an alumina refinery in Australia.
Published: October 20, 2017

Detailed Description of Converting Dry Contacts to Analog Signals

Before converting a dry contact to an analog signal it is important to first determine what signal levels you will need.  Since the TMZ accepts a 4-20mA signal then we can choose any current values within 4mA and 20mA.  For this application we chose 'NOT FULL' to be equal to 20mA, and “NEAR FULL” to be represented at 4mA. 

 

Published: October 11, 2017
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