Siemens
Siemens 3RT20 S3 Contactor 3P 90–110 A AC-3 45–55 kW 220 V AC Coil | Magnetic Motor Contactor
Siemens 3RT20 S3 Contactor 3P 90–110 A AC-3 45–55 kW 220 V AC Coil | Magnetic Motor Contactor
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The Siemens 3RT20 S3 is a 3-pole power contactor rated 90–110 A in AC-3 (motors of about 45–55 kW at 400 V) with a 220 V AC coil. It switches three-phase motors, heaters, lighting groups and capacitor steps remotely from push buttons, PLCs, float switches, pressure switches or timers, and combines with a thermal overload relay or MPCB to form a complete motor starter. This listing covers several ratings – choose the version that matches the motor current.
Key features
- 90–110 A AC-3 rating for motors of 45–55 kW
- Coil 220 V AC
- Long electrical and mechanical life for frequent switching
- Add-on auxiliary contacts, timers, surge suppressors and mechanical interlocks
- Direct mounting of matching thermal overload relays
- DIN-rail or screw mounting (frame dependent)
Technical specifications
| Brand | Siemens |
|---|---|
| Part number / model | 3RT20 S3 |
| Device type | Power contactor (3-pole) |
| Rated operational current AC-3 | 90–110 A |
| Motor power AC-3 at 400 V | 45–55 kW |
| Coil voltage | 220 V AC |
| Poles | 3 NO main poles |
| Standard | IEC/EN 60947-4-1 |
Available versions
Current Rating: 90A / 45 kW, 110A / 55 kW.
Typical applications
- Water pumps, booster and sewage pumps
- DOL, star-delta and reversing starters
- HVAC compressors, fans and cooling towers
- Heater and lighting control
- Capacitor banks, cranes and conveyors
Selection and installation tips
Select the contactor by the motor full-load current in AC-3 rather than kW alone, choose the coil voltage to match the control circuit (220–230 V AC is the most common in Egypt), and add a thermal overload relay whose setting range covers the motor current.
Frequently asked questions
What motor size can the Siemens 3RT20 S3 control?
It is rated 90–110 A in AC-3 duty at 400 V, which corresponds to three-phase motors of about 45–55 kW.
What is AC-3?
AC-3 is the IEC utilisation category for starting and stopping squirrel-cage motors – the standard rating used to select motor contactors.
Do I need an overload relay with the contactor?
Yes. A contactor only switches the motor; protection against overload must be provided by a thermal overload relay or a motor protection circuit breaker.
Buy Siemens 3RT20 S3 in Egypt
Spark Egypt is a trusted source for original Siemens products such as the 3RT20 S3 magnetic contactor, serving contractors, OEMs, panel builders, facility managers and home owners with tax invoices and fast delivery to Cairo, Giza, New Cairo, 6th of October, Sheikh Zayed, the New Administrative Capital, Alexandria, the Delta, the Canal cities and Upper Egypt. Contact our sales team to confirm selection, compatible accessories and project pricing.
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