Motor being electro-mechanical equipment, apart from electrical protection, it is important to protect the motor from accidental human contact, ingress of foreign material like dust, water is equally important. These protections are classified depending upon the location of the motor under use. "mototek" motors are normally available with IP55 protection as standard. Better protections are provided as required. The "mototek" motors are provided with IP protection as per EN 60034-5. IS 4691.
It is recommended to use a rain guard with clear air flow cover when the motor needs to be mounted in V1, V5, V15 or V18 mounting position. The canopy type construction on the rear, air suction side of the fan cover prevents the rain water to enter the fan area. Similar protection can be used in textile processing or such areas to counteract fiber or such waste from surroundings. The total length of the motor increases with such protection marginally but motor will be protected to a great extent.
It is a standard practice to protect motors against over current by overload relays, fuses or MCBs. For thermal protection, motors can be supplied with thermister or thermal switch. For condensing environments, motors with space heaters can be supplied as well. The table below gives general idea for selection of fuse ratings and over load relays.
DOL starting
| kW/HP | 0.37/0.5 | 0.55/0.75 | 0.75/1.0 | 1.1/1.5 | 1.5/2.0 | 2.2/3.0 | 3.7/5.0 | 5.5/7.5 | 7.5/10 | 9.3/12.5 | 11/15 | 15/20 | 18.5/25 | 22/30 | 30/40 | 37/50 | 45/60 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Average Current | 1.1 | 1.4 | 1.9 | 2.6 | 3.7 | 4.8 | 7.8 | 11.2 | 15 | 18 | 21 | 27 | 33 | 39 | 53 | 65 | 78 |
| Fuse Rating | 4 | 6 | 6 | 6 | 10 | 16 | 16 | 25 | 25 | 35 | 35 | 50 | 63 | 63 | 100 | 100 | 160 |
| Relay Range | 1-2 | 1-2 | 1-2 | 2-4 | 2-4 | 3-6 | 6-12 | 6-12 | 10-16 | 18-24 | 18-24 | 16-32 | 24-45 | 24-45 | 32-63 | 50-90 | 50-90 |
STAR-DELTA starting
| kW/HP | 3.7/5.0 | 5.5/7.5 | 7.5/10 | 9.3/12.5 | 11/15 | 15/20 | 18.5/25 | 22/30 | 30/40 | 37/50 | 45/60 | 55/75 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Line | 7.8 | 11.2 | 15 | 18 | 21 | 27 | 33 | 39 | 53 | 65 | 78 | 92 | |
| Average Current | Phase | 4.5 | 6.5 | 9 | 11 | 12.7 | 16.8 | 20.2 | 23.2 | 30.6 | 37.5 | 46.4 | 53.2 |
| Fuse Rating | 16 | 25 | 25 | 35 | 35 | 50 | 63 | 63 | 100 | 100 | 160 | 200 | |
| Relay Range | 1.5-3 | 4-8 | 6-12 | 6-12 | 10-16 | 18-24 | 18-24 | 18-24 | 16-32 | 24-45 | 32-50 | 50-63 | |