At a Glance. A Bently Nevada 3500 rack is not one device - it is a stack of modules that must be ordered as a working set. Miss one piece and the monitor cannot power up or talk to your DCS. This guide maps every stocked module to its role: the 3500/15 power supply feeds the rack, the 3500/22M Transient Data Interface is the communication backbone, the 3500/25 Keyphasor provides the once-per-revolution reference, the 3500/42M turns proximity and seismic signals into alarms, and the 3300 XL probes sense the shaft. The TK-3E simulates a probe so you can loop-test the whole chain before startup.
1. The 3500 Rack, Module by Module
| Module | Role in the rack |
|---|---|
| 3500/15 Power Supply | Powers the entire rack; order one (or two for redundancy) matched to your supply voltage |
| 3500/22M TDI | Transient Data Interface - the rack-to-software communication and data gateway |
| 3500/25 Keyphasor | Enhanced Keyphasor - converts a once-per-revolution pulse into the phase reference all monitors use |
| 3500/42M | Proximitor/Seismic monitor - radial vibration, axial thrust and seismic measurement channels with alarms |
| 3300 XL 8mm | Standard 8 mm proximity probe system - the workhorse for radial shaft vibration |
| 3300 XL 5mm | Miniature 5 mm probe - for tight installation spaces and small targets |
| TK-3E | Eddy-current simulator - verifies probe-to-monitor loops without spinning the machine |
2. Minimum Workable Configuration
A single radial-vibration channel needs, as a set: one 3500/15 power supply, one 3500/22M TDI, one 3500/25 Keyphasor (fed by a Keyphasor pickup), one 3500/42M monitor, and a 3300 XL 8mm probe system per measurement point. Practical ordering advice from years of supplying these racks: budget the probes and the rack electronics as one line item - half-finished racks are the most common failure we see in retrofit tenders.
For machines that do not justify a full 3500 rack (pumps, fans, small motors), the 1900/65A general-purpose monitor is the standalone alternative - it covers the same measurement families without the rack infrastructure. Our earlier comparison covers the 3500/42M vs 1900/65A decision in detail.
3. Probe Selection: 8 mm vs 5 mm
- 3300 XL 8mm: the default for radial vibration and axial position on standard machines - best availability of probes, extensions and Proximitor sensors;
- 3300 XL 5mm: miniature version for confined probe mounting, small shafts or embedded installations where the 8 mm cannot fit.
Both feed the same 3500/42M monitor family, so the choice is set by the mechanical installation, not the electronics.
4. Commissioning Tip: Test Before You Spin
Before the machine runs, connect the TK-3E simulator in place of the probe: it generates a controlled eddy-current signal so you can verify gap voltage, scaling, alarm setpoints and DCS communication through the 22M. Ten minutes with a TK-3E routinely saves a failed startup call-out.
5. Replacement and Cross-Reference
Typical replacement patterns:
- Failed monitor channel: replace like-for-like with the 3500/42M - confirm the option configuration (channels, alarm logic) matches the old module before ordering.
- End-of-life 3300 series components: the 3300 XL 8mm system is the current-generation successor - probe, extension cable and Proximitor sensor should be replaced as a matched set for correct scaling.
- Rack power issues: check the 3500/15 before blaming monitors - a sagging supply produces intermittent faults across every slot.
Send Glorient your rack slot map or the old module faceplates, and we will confirm the exact Bently Nevada configuration from stock within one business day.
6. FAQ
Can I mix 3300 XL probes with an older 3300 monitor?
The 3300 XL probe system is the current generation and is used with 3500-series monitors such as the 3500/42M. For legacy 3300 racks, confirm component compatibility as a set - probe, extension and Proximitor must match generation and length.
Do I need the 3500/25 Keyphasor module?
Yes for anything beyond basic amplitude trending - phase, orbit plots and transient analysis through the 22M all depend on a Keyphasor reference from the 3500/25.
1900/65A or full 3500 rack for a pump skid?
For a few measurement points on general-purpose machines, the standalone 1900/65A is faster and cheaper to deploy. Reserve the 3500 rack for critical trains where the TDI software ecosystem earns its cost.
Need a quote? Browse in-stock Bently Nevada modules - 3500 rack electronics, 3300 XL probe systems and monitors - or send your machinery list for a same-week configuration and quotation.