Allen Bradley509-FODNEMA Size 5 Full-Voltage Non-Reversing Magnetic Motor Starter, 270 A, 600 V AC, 120 V Coil, Open Type, Eutectic Alloy Overload

Product Description

What this part is

A NEMA Size 5 full-voltage non-reversing magnetic motor starter from Allen-Bradley’s Bulletin 509 range: a three-pole across-the-line contactor with a thermal overload relay bolted to it, forming a complete starter. Full voltage means it applies the full line voltage to the motor in one step — a direct-on-line start, with the inrush that implies — and non-reversing means it has one contactor and drives the motor in one direction only.

Decoding the catalogue number

509 — Bulletin 509: NEMA full-voltage non-reversing starter with overload relay. (Bulletin 500 is the contactor alone; 512 is the reversing starter.)F — NEMA Size 5. This letter is the rating and it is the first thing to check: Size 5 is 270 A continuous.O — Open type, without enclosure. This is a bare starter for mounting inside a customer’s own panel or existing enclosure. It has no cover, no door, no enclosure rating and no operator devices.D — 115–120 V, 60 Hz operating coil. The coil-voltage letter is the second thing to check and the most common source of a wrong order: the sibling 509-FOB is the same starter with a 460–480 V coil. A 120 V coil on a 480 V control circuit will fail immediately, and a 480 V coil will not pull in on 120 V.SER L — hardware series L, a manufacturing revision within a long production run.

Published ratings

NEMA size: 5Continuous current rating: 270 AMaximum voltage: 600 V ACPoles: 3Operating coil: 115–120 V, 60 HzOverload relay: eutectic alloy thermal type (the classic melting-alloy ratchet design), manual resetMotor rating: up to 200 HP at 460 V AC three-phase. Horsepower is voltage-dependent — at lower supply voltages the same 270 A carries proportionally fewer horsepower, which is why the range across 200–575 V is quoted as a band rather than a single figure. Size the starter on motor full-load amperes against 270 A, not on the horsepower headline.Construction: open type, panel mounting, no enclosure

What these ratings mean in practice

Size 5 is genuinely large gear — this is switchgear for a 100 to 200 HP motor, and it is heavy, physically substantial and needs real conductor and lug provision. Before ordering, confirm three things against your application: the motor’s full-load current sits comfortably inside 270 A, the control voltage is 120 V AC (not 240 V, not 480 V, not DC), and you have an enclosure or panel to mount it in.

The overload relay is a eutectic alloy design, which matters for how you set it up. It does not have a dial you turn to the motor FLA. Protection is set by fitting heater elements chosen from Allen-Bradley’s selection tables for the specific motor full-load current, service factor and ambient. The heater elements are not included with this starter. Without correctly sized heaters the starter will either not protect the motor at all or will trip on every start — and it is the single most frequently overlooked item when buying a used NEMA starter.

Full-voltage starting also means full inrush: six to eight times motor FLA for the duration of the start. On a 200 HP motor that is a serious transient. If your supply cannot take it, or the driven load cannot take the torque step, a reduced-voltage starter, soft starter or VFD is the right answer rather than this.

Quantity and configuration

One starter assembly, used, in good condition as photographed.

What is not included

Overload heater elements (must be selected for your motor), enclosure or cover, back panel or mounting plate, lugs and cable terminations, control transformer, fuses or circuit breaker, start/stop pushbuttons, pilot lights or operator devices, auxiliary contact blocks beyond those fitted, replacement main or arcing contacts, coil beyond the one fitted, mounting hardware, and documentation. This is the bare open starter.

Installation and inspection notes

On any used Size 5 starter, inspect the main contacts before commissioning: look for pitting, mushrooming, burnt silver facing and uneven wipe across all three poles. Contacts are a wear item and a replacement contact kit is a normal part of putting a used starter into service. Check that the armature moves freely and that the coil ohms are sensible for a 120 V coil. Confirm the overload relay’s reset mechanism operates and that the eutectic alloy tube heaters have not been over-heated in a previous life.

Torque the power connections to specification and observe the required clearances — open-type gear has no barriers, so the enclosure and the layout are providing all the isolation. Verify heater element selection against the motor nameplate FLA, not against the starter size.

Interchange guidance

Direct interchange with other 509-FOD starters of any series letter. Related but different parts, not equivalents: 509-FOB (460–480 V coil), 509-FOA / 509-FOC and other coil-suffix variants, 509-FOD-A2N (same starter with an E1 Plus solid-state overload relay instead of eutectic alloy), 500-FOD (contactor without overload relay), 512-series (reversing), and the enclosed 709-series equivalents. Size letters E and G are Size 4 and Size 6 — different current ratings entirely. Match the size letter, the coil letter and the overload type.