Guides · TOSUNLUX
Which contactor and which thermal overload relay for a 1.5 to 75 kW motor?
A motor starter combines three functions: clearing short circuits, protecting the motor against overloads, and switching it. With the TOSUNLUX (Tosun) range, this is done either with a motor circuit breaker and a contactor, or with a contactor and a thermal overload relay.
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The short answer
- Choose the contactor from the motor power in AC-3 at 400 V: TSC1-D from 4 to 75 kW.
- Set the protection to the current on the motor nameplate, not to its power.
- Up to 18.5 kW, an MP2 / MP3 motor circuit breaker protects against both overloads and short circuits.
- With a contactor alone, add a TSR2-D thermal overload relay and short-circuit protection upstream.
The table: motor power → devices
Powers in category AC-3 (squirrel-cage motor, direct-on-line start, switching off while running) at 400 V three phase, from the FAPELEC catalogue. The contactor shown is the smallest whose AC-3 power covers the motor.
| 400 V motor | TSC1-D contactor (AC-3 400 V) | Motor circuit breaker (setting range) |
|---|---|---|
| 1.5 kW | TSC1-D09 (4 kW) | MP2-M08 (2.5–4 A) |
| 2.2 kW | TSC1-D09 (4 kW) | MP2-M10 (4–6.3 A) |
| 4 kW | TSC1-D09 (4 kW) | MP2-M14 (6–10 A) |
| 5.5 kW | TSC1-D12 (5.5 kW) | MP2-M16 (9–14 A) |
| 7.5 kW | TSC1-D18 (7.5 kW) | MP2-M20 (13–18 A) |
| 11 kW | TSC1-D25 (11 kW) | MP2-M21 (17–23 A) or MP2-M22 (20–25 A) |
| 15 kW | TSC1-D32 (15 kW) | MP2-M32 (24–32 A) |
| 18.5 kW | TSC1-D40 (18.5 kW) | MP3-M40 (25–40 A) |
| 22 kW | TSC1-D50 (22 kW) | — |
| 30 kW | TSC1-D65 (30 kW) | — |
| 37 kW | TSC1-D80 (37 kW) | — |
| 45 kW | TSC1-D95 (45 kW) | — |
| 55 kW | TSC1-D115 or TSC1-F115 (55 kW) | — |
| 75 kW | TSC1-D150 or TSC1-F150 (75 kW) | — |
Set the protection to the nameplate current
Two motors of the same power do not necessarily draw the same current. Overload protection is always set to the rated current read on the motor nameplate. With a motor circuit breaker, choose the model whose setting range contains that current; the same goes for the thermal overload relay.
| Thermal overload relay | Setting range | Frame |
|---|---|---|
| TSR2-D1308 | 2.5 – 4 A | D13 |
| TSR2-D1310 | 4 – 6 A | D13 |
| TSR2-D1312 | 5.5 – 8 A | D13 |
| TSR2-D1314 | 7 – 10 A | D13 |
| TSR2-D1316 | 9 – 13 A | D13 |
| TSR2-D1321 | 12 – 18 A | D13 |
| TSR2-D1322 | 17 – 25 A | D13 |
| TSR2-D3353 | 23 – 32 A | D33 |
| TSR2-D3355 | 30 – 40 A | D33 |
| TSR2-D3357 | 37 – 50 A | D33 |
TSR2-D thermal overload relays cover 2.5 to 50 A in ten ranges and plug directly under TSC1-D contactors. They also protect against single-phasing (loss of a phase).
Coil, auxiliary contacts and assemblies
The TSC1-D contactors in the FAPELEC catalogue come with a 220 V or 380 V coil (and 24 V AC for D12 and D25). Models D09 to D32 have one built-in NO or NC auxiliary contact, D40 to D95 one NO+NC. With an auxiliary block, a timer or a mechanical interlock, two or three contactors form a reversing starter or a star-delta starter.
On 230 V single phase, use the "P AC-3 230 V" column of the TSC1-D sheet: for example 2.2 kW for the D09 and 4 kW for the D18.
AC-3 or AC-4?
AC-3 is the normal use of a motor: direct-on-line starting and switching off while running. AC-4 (inching, plugging, reversing at full speed) wears the contacts much more: the permissible current drops, for example 3.5 A in AC-4 against 9 A in AC-3 for the TSC1-D09. For these duties, oversize the contactor.
Frequently asked questions
Which contactor for a 4 kW motor at 400 V?
The TSC1-D09, rated 4 kW in AC-3 at 400 V, with a thermal overload relay set to the motor nameplate current or an MP2-M14 (6–10 A) motor circuit breaker.
Motor circuit breaker or thermal overload relay?
The MP2 motor circuit breaker protects against overloads and short circuits in a single device, up to 18.5 kW in the catalogue. The thermal overload relay only protects against overloads: short-circuit protection is needed upstream.
How to set a thermal overload relay?
To the rated current shown on the motor nameplate, choosing the TSR2-D relay whose range contains that value.
Which contactor for 75 kW?
The TSC1-D150 or the TSC1-F150, rated 75 kW in AC-3 at 400 V.
TOSUNLUX series mentioned
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