Manufacturing, Plant Safety, Safety Relays on Transmitters, Transmitters

Diagnostics that Reach Beyond their Normal Boundaries

As a company known for our pressure and temperature switches, transmitters and sensors for safety, alarm and shutdown applications; we’re constantly evaluating our customers’ needs. Our range of product offerings, including the One Series Safety Transmitters, are engineered to meet and exceed industry standards.

It all started with our One Series electronic switch product line, originally introduced in the late 1990s. During focus group interviews with our customers, it was determined that these products must include self-diagnostic capability, helping to avoid the “blind switch issue” inherent in mechanical switches (which we also manufacture). In a blind switch intended for safety, customers were concerned about reliability. “How do I know if will work when I need it to?”

The blind switch issue was a major consideration when designing our One Series Safety Transmitter because when a product is “blind,” it has no self-diagnostic capability, requiring preventative maintenance to determine if it is still functional Additionally, the reduction in the number of maintenance workers leaves fewer instrument and control technicians to perform this vital maintenance, a concern for plant managers. Plant upgrade strategies now specify self-diagnostic (smart) instrumentation, such as our One Series Safety Transmitter.One Series Safety Transmitter Display

 

At United Electric Controls, we go beyond the traditional boundaries of self-diagnostic instrumentation. For example, typical smart instruments can determine if there are errors in the software, if the sensor cable is disconnected and if there is a functioning keypad to set parameters. The One Series IAWTM self-diagnostics take this concept much further and evaluate the sensor to see if it is open, shorted and still capable of sensing temperature and pressure, is there a button stuck on the keypad and the validity of the signal that is telling the switch to open. This is all important so there is reasonable assurance that the product is functioning correctly and safely.

The One Series IAWTM self-diagnostic feature also considers external influences on the operation of the product, evaluating the power that the instrument is being given, loop power or DC power supply. The One Series monitors the power supply to make sure the power is clean, and there are no spikes, drooping, or noise from radio frequencies, etc. This is all done to make sure the power source is reliable.

The One Series can also detect if the sensor is clogged and unable to read pressure. The One Series has an advanced feature called Plug Port Detection to determine if the sensor is clogged and then can report the condition as detailed below. Another external diagnostic feature involves the ability to monitor the Safety Relay Output from an external perspective. For example, if the instruction to open the SRO is given by the microcontroller, IAWTM can determine if the SRO actually opened. Line fault detection is also included to detect open and shorted wiring connections to the final element (load).When IAWTM detects a fault, three actions are taken:

  1. The process variable and IAW indicator is replaced by a message on the display, informing the I&C technician of the fault type.
  2. The NAMUR NE 43 standard 4-20 mA output will change from indicating the process variable to the fault indicating current of 3.6 mA, providing remote indication to the control system that a fault has occurred.
  3. The Safety Relay Output (SRO), SRO Status and IAW outputs will fail safe (open) within 100 milliseconds of the detected fault, initiating an emergency shutdown.

Consider the One Series family of pressure and temperature monitors for your safety, alarm and shutdown applications. Click here for more details.

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