PCBA protoyping for 3500 machinery protection system
Orbit Article

So, you have a 3300 rack … Now what?!

7 min read
Nigel Leigh
Product Line Manager

When the 3300 Monitor was introduced in 1987, the Bently Nevada Catalog made 
a strong statement:

“Highly reliable machinery information is essential for improved plant performance”

True to the Bently Nevada reputation for quality, many 3300 monitors are still functional and in use today (around 30 years later)!In fact, we occasionally see even earlier monitors in use.

In fact, we occasionally see even earlier monitors in use.

Rack Based Monitoring Systems History

As with any electronic device, aging components can put protected equipment at risk of false-trips or missed-trips, should they fail unexpectedly in operation.  Because 3300 was designed & built in 1987, many electronic subcomponents on the circuit boards are no longer available.  As a result, we’ve been slowly phasing out the 3300:

  • Mid-2009:       the system was moved entirely to spare part support only (Phase 3)
  • Feb 2011:       status downgraded to “repairs only” (Phase 4)
  • March 2014:   classified as obsolete, meaning the product has no (or limited) support and is not recommended for continued use in a machinery protection application (Phase 5). In fact, limited repairs were possible until 2017.

If you’re reading this and you have a 3300 in your facility (or an even earlier monitor), your next question is likely “great, so we have some obsolete hardware … now what?!”. The remainder of this article explores some options for you to choose from. As always, please contact your local Bently Nevada representative if you have any questions or would like to investigate further options.

Bently Nevada has been your trusted source of highly reliable machinery information for the last 60 years – and we’re here to help you for the next 60+ years!

Bently Nevada Rack
Choosing a Path Forward

Here’s a summary of your key options, with further details in the following sections.

Choosing a path forward
Bently Nevada Services
Bently Nevada Services

If your 3300 system has been operating for a long time, it may have been a while since you’ve had it properly checked. If a technology update is not in the immediate future, it is strongly recommended to have a qualified Bently Nevada representative perform an overall health check of your primary monitoring system. Due to the increased risk of component failures with aging instrumentation, our services will verify that your 3300 is in working condition, plus verification, removal, and re-installation (as needed) for all related transducer systems. The health check performed by the Bently Nevada Services team would include actions such as:

Monitoring System(s) Health Check

  • Thorough visual inspection of the rack and enclosure
  • Verification of communication channels to communication processor and System 1*/Data Manager software (if present)
  • Comprehensive calibration check
  • Relay operation assessment and confirmation that all configured relay logic is operational
  • Verification of communication to third party devices e.g. DCS

Transducer Inspection and Replacement Services

  • All-inclusive assessment of individual transducers throughout monitoring operation
  • Identification/Removal of any faulty transducers
  • Re-installation of all required transducers per Bently Nevada’s “Best Practice” installation guidelines
  • Validation that monitoring loop is fully operational

Once complete, you will receive a comprehensive report detailing the condition of your machinery protection system that includes any recommended actions. It is recommended to perform a Health Check at least once a year on older monitoring systems to ensure that your equipment and your people are protected properly.

3500 (preferred)
3500 Machinery Protection Systems

The 3500 is the result of decades of experience in the condition monitoring & protection field… With features like 1X, 2X, not 1X variables, extensive fault tolerant design, RF immunity, ease of configuration, etc. – the 3500 is an improvement on the 3300 in almost every way. And with a standardized 19” size  and 4-channel cards that are less than an inch wide, the channel density possible in a 3500 is far greater than a 3300. Several application-specific monitors are also available (recip compressor, hydro, aeroderivative gas turbine, etc.), making it the ideal solution for all your condition monitoring & protection needs. 

The 3500 has a huge installed base of over 80,000 monitors with over 4,000 more shipping annually. The 3500 remains in phase 1 of its product lifecycle, including support for enhancements, custom product development, new systems and global projects. The system recently underwent a complete refresh and redesign. We are committed to provide 3500 support for many years.    

The 3500 Series Machinery Monitoring System is also designed to communicate directly with System 1® software for state-of-the-art machinery condition monitoring & diagnostic capabilities.  This ensures that along with industry trusted machinery protection, you also have access to effective machinery condition monitoring tools, so you are well informed about the health of your machines. Understanding their condition allows you to more effectively plan maintenance cycles and optimize planned down time for these critical assets.

If replacing a 3300 mounted in a panel, the cutout will need to be modified slightly. The 3500 is 0.78” taller than the 3300. And because the 3300 was available in 4, 6, 8, 10, 12, 14-position variants, the width opening may need to be enlarged or reduced accordingly. However, if a complete upgrade is being considered, the 3500 rack is designed to fit into a standard 19” cabinet rack-mount. Your local Bently Nevada Services team can assist in any re-designs that may need to be done.

The sensor field wiring can be easily transferred from the original 3300 rack to the new 3500 rack’s backplane (provided it is still in acceptable condition).

3701 ADAPT
Adapt Platform

While not a comprehensive replacement for a 3300, the ADAPT platform may prove to be a viable alternative and a significant performance upgrade in the following situations:

  • The point count is low
    • ≤ 12 vibration points & 2 Keyphasor/speed points
  • Complex calculations are required 
    • rolling element bearings, gearboxes
  • A more distributed architecture is desired
    • Monitor mounted close to the machine, with a single communication cable.
Other Monitors

When the 3300 was introduced, it was the primary hardware format that Bently Nevada offered. As times change, so do we. Bently Nevada now has other monitors which offer alternatives to the 3300’s rack-based format.

Other Monitors

See full details:

Remind me, why should I upgrade?
“Our 3300 racks have served us well for two or three decades, 
why should we worry about them now?”

The reality is that the 3300 components are old, and many are not replaceable. Electrolytic capacitors, electro-mechanical relays, front panel buttons, and Electrically Erasable Programmable Read Only Memory are all wearable components with finite lifespans. These lifespans are in the 12 to 30-year range, and are highly dependent on usage, operating temperature & environment. You may have a stock of 3300 spare parts, but note that some of their components are still aging during storage.

Repair & replacement support for the 3300 system ended completely in 2017, so it would be prudent to plan for a proactive system upgrade. Updating these systems prior to a failure can provide substantial savings, compared to reacting to a sudden failure which cannot be repaired, nor a spare module purchased.  This type of event may prevent you from operating your machine until a system update is performed, leading to substantial unplanned down time.

But upgrading isn’t just about risk avoidance, it can also open new opportunities for efficiency. Like the ability to connect to the latest version of System 1 software, for its state-of-the-art machinery condition monitoring & diagnostic capabilities. 3500, 3701, 2300 & vbOnline Pro all have this capability. Get connected, Get Insights, Get Optimized.



Bently Nevada has always prided itself on long-term support for its products. The 3300 is no exception. With a 30-year lifespan, the 3300 has served the market well.  Now is the time to act, prior to instrument failure and costly down time. Take advantage of Bently Nevada’s comprehensive range of monitoring solutions to keep your plant running safely and reliably.