Description
The ABB MS495 (Order Code: 1SAM550000R1008) is a compact Manual Motor Starter (MMS) / Motor Protection Circuit Breaker (MPCB) from ABB’s MS495 series, designed to provide manual ON/OFF switching, overload protection (adjustable bimetal), short-circuit protection (fixed magnetic instantaneous trip), and phase-failure (phase-loss) sensitivity for three-phase AC induction motors up to approximately 0.37–0.55 kW at 400 V. It combines the functions of a disconnect switch, overload relay, and short-circuit protector in a single 45 mm wide DIN-rail device, typically mounted alongside an ABB AF contactor in a starter combination.
Application Scenarios
A packaged water-booster skid used three 0.37 kW stainless-steel centrifugal pumps, each controlled by an ABB AF09 contactor. Originally protected by separate thermal overload relays and a fused isolator, the panel was crowded and required frequent re-fusing after nuisance trips. The OEM replaced the fuse-holder + OL relay with ABB MS495 1SAM550000R1008 manual motor starters — set to the motor’s FLA of 0.85 A via the front dial. During commissioning, a single-phase voltage loss on L2 caused the MS495’s phase-loss sensitive bimetals to trip within minutes — alerting the panel builder to a loose terminal before the motor could overheat. The built-in test/reset button and clearly marked current-adjustment dial saved time during site acceptance testing. The skid designer commented: “The 1SAM550000R1008 shrank our starter width by 35 mm per pump, eliminated fuses, and gave us phase-loss protection we didn’t have before. It’s now our standard MMS for anything ≤1 A motor rating.”
Parameter
| Main Parameters | Value/Description |
|---|---|
| Product Model | MS495 (Specific: 1SAM550000R1008 = MS495-1.0A) |
| Order / Article No. | 1SAM550000R1008 |
| Manufacturer | ABB (Control Products — MS495 Series Manual Motor Starters / MPCB) |
| Product Category | Manual Motor Starter / Motor Protective Switch (MPS) / MMS |
| Poles | 3 (3-phase, 3NO main contacts) |
| Rated Operational Current (Ie) | Adjustable 0.63–1.0 A (thermal OL range) |
| Rated Operational Voltage (Ue) | Up to 690 V AC (50/60 Hz); 250 V DC (limited poles) |
| Magnetic Trip (Short-Circuit) | Fixed 13 × Ie max ≈ 13 A instantaneous (non-adjustable, for short-circuit protection up to 50 kA @ 400 V with proper upstream coordination) |
| Motor Rating (Typical) | ≤ 0.37 kW @ 400 V AC (AC-3), ≤ 0.55 kW @ 230 V AC |
| Rated Insulation Voltage (Ui) | 690 V AC |
| Rated Impulse Withstand (Uimp) | 6 kV |
| Operating Temp. | -25 °C to +60 °C (-13 °F to +140 °F) |
| Mounting | 35 mm DIN rail (TH35), 45 mm width |
| Switching Capacity | Make: 10 × Ie; Break: 1.5 × Ie (AC-3 duty) |
| Phase-Loss Protection | Yes — bimetal elements are phase-loss sensitive (trips on loss of any one phase) |
| Handle / Operation | Black rotary handle: OFF — 0 — ON; padlockable in OFF position (up to 3 locks) |
| Auxiliary Contacts | Optional side-mount (early-break NC for door interlock, NO/NC alarm, UNDERVOLTAGE release MX, shunt-trip MN — sold separately) |
| Terminal Capacity | Rigid: 1× 1.5–10 mm²; Flexible: 1× 1.5–6 mm² + ferrule |
| Standards | IEC 60947-1, IEC 60947-4-1 (Motor Starters), IEC 60947-2 (Circuit-Breakers), UL 508, CSA, CCC |
| IP Rating | IP20 (fingersafe IP2X terminals with shrouds), IP40 with optional front cover |
Technical Principles and Innovative Values
The ABB 1SAM550000R1008 (MS495) consolidates three conventional devices into one certified enclosure-mount unit:
- Innovation Point 1 — True Phase-Loss Sensitive Bimetal Overload: Unlike some electronic OL relays that require an auxiliary supply, the MS495’s three independent bimetal strips respond to heating from motor current in each phase. If one phase is lost (e.g., blown fuse upstream, loose terminal), the remaining two phases heat faster and trip — typically within the UL / IEC stipulated time — protecting the motor from single-phasing damage.
- Innovation Point 2 — Fixed High-Breaking-Capacity Magnetic Instantaneous Trip: The electromagnetic trip coil is calibrated to 13 × Ie_max (≈13 A for the 1.0 A frame) and is series-connected in all three poles. It responds in < 0.1 s to short-circuit faults without relying on fuse clearing, allowing coordinated protection when backed by appropriately rated upstream MCB/MCCB.
- Innovation Point 3 — Padlockable OFF Handle & Clear Current Dial: The rotary handle can be locked in the OFF (0) position with up to three padlocks — satisfying LOTO/OSHA requirements. The front-mounted current-setting dial is directly calibrated in amps (0.63–1.0 A) with a clear pointer, eliminating guesswork during commissioning.
- Innovation Point 4 — Side-Mount Expandability (No Wiring Changes): The MS495 accepts ABB’s full range of side-mounted accessories — auxiliary contact blocks (1NO+1NC early-break), undervoltage release (MX), shunt-trip (MN), and alarm contacts — clipped onto the left or right side without altering the main power terminations or DIN-rail footprint.
