Description
Application Scenarios
A combined-cycle power plant runs its steam turbine generator set on a Bently Nevada 3300 rack: shaft vibration, axial position, differential expansion, eccentricity and speed, spread across a dozen monitor modules with transducers cabled out to the machine hall. That rack is the last line of protection between a developing rotor problem and a catastrophic failure, and every channel on it depends on one component — the 3300/12 in position 1.
Two things about that dependency matter in practice. The first is that the rack is old enough that the plant’s documentation no longer matches what is installed. When the supply shows signs of ageing, the engineer cannot just order a “3300/12”: the ordering code encodes input voltage, Power Input Module type and agency approval, and getting it wrong means a module that either will not run on the available mains or lacks the hazardous-area approval the site’s classification requires. Reading the model number off the existing unit — and knowing that option 01 is the 115 V range, option 02 the 230 V range, option 22 internal safety barriers, and option C the approval — is what turns a parts purchase into a correct one.
The second is the failure mode that nobody sees coming. A power supply on a protection rack does not simply “stop”; it can drop the transducer supply while the monitors still appear powered, or a single monitor board can fail in a way that leaves the machine turning with no vibration protection and no operator aware of it. That is what the 3300/12‘s OK relay exists for. It is normally energised, and it changes state on loss of primary power, on a monitor failure, and on a transducer wiring fault — so when the plant wires those contacts to an external annunciator, the loss of protection announces itself instead of sitting silently until the next incident.
Parameter
| Main Parameters | Value / Description |
|---|---|
| Product Model | 3300/12 — ordering format 3300/12-AXX-BXX-CXX. A = input voltage (01 = 95–125 V AC, 02 = 190–250 V AC), B = Power Input Module (20 = standard, 22 = internal safety barriers, 23 = spare supply only, no PIM), C = agency approval (00 = none, 01 = CSA/NRTL/C Class I Div 2, 02 = ATEX self-certification) |
| Manufacturer | Bently Nevada |
| Product Category | AC power supply module for the 3300 Series machinery monitoring rack |
| Rack Position | Position 1, the left-most slot; occupies one rack position. A second power supply is never required in the same rack |
| Load Capacity | Supplies regulated power for up to 12 monitor modules and their associated transducers |
| Input Voltage | Field-selectable: 95–125 V AC single phase at 50/60 Hz, 1.0 A maximum; or 190–250 V AC single phase at 50/60 Hz, 0.5 A maximum |
| Input Range Change | Field-changeable via a soldered jumper and external fuse replacement — no different module needed to move between 115 V and 230 V sites |
| Power-Up Surge | 26 A peak or 12 A rms for one cycle — size upstream protection and contactors for the inrush, not the steady-state current |
| Fuse Ratings | 250 V, 1.5 A slow-blow for the 95–125 V AC range; 250 V, 0.75 A slow-blow for the 190–250 V AC range. ATEX-approved configurations use 2.50 A and 1.25 A respectively |
| Transducer Power Output | Jumper-programmable: −24 V DC (+0%, −2.5%) or −18 V DC (+1%, −2%) — selected to match the transducer population in the rack |
| Output Protection | Per-channel overload protection located on the individual monitor circuit boards, so a shorted transducer loop does not take down the rack supply |
| OK Relay | Single-pole double-throw (SPDT), hermetically sealed, normally energised; located behind the power supply at the Power Supply Input Module |
| OK Relay Contact Ratings | 5 A at 28 V DC; 5 A at 120 V AC, 50/60 Hz; 3 A at 220 V AC (resistive). 5 A at 28 V DC and 120 V AC for ATEX configurations. Contact life 10,000 cycles minimum at rated load |
| OK Relay Function | Changes state on loss of primary power, monitor failure, or transducer wiring failure — the single most useful signal on a protection rack |
| Line Filtering | Integrated line noise filter fitted as standard, for stable operation in electrically noisy industrial switchrooms |
| Physical & Environmental | Occupies one rack position, approx. 1 kg; operating 0 °C to +65 °C, storage −40 °C to +85 °C; up to 95 % relative humidity, non-condensing |
| Spare Parts | Power Input Module assembly 161956-AXX-BXX-CXX; fuses 01701500 (250 V, 1.5 A), 01703118 (250 V, 0.75 A), 01710512 (250 V, 2.50 A), 01720007 (250 V, 1.25 A); transformer assemblies 147262-01 and 147262-02 |
