Every motor must be protected from all possible faults to ensure prolonged and safe operation as well as time loss caused due to breakdown. Almost all the industries rely on the electric motor to control its processes and production. Hence it is necessary to make the motor fail-safe.
The time taken by them to open the contactor during overloads is specified by the trip class. It is commonly classified into Class 10, Class 20, Class 30 and Class 5. The OLR trips in 10 seconds, 20 seconds, 30 seconds and 5 seconds respectively at 600% of full load current to the motor. Class 10 and Class 20 are very commonly used ones. Class 30 overload relay are used for protection of motors driving high inertia loads and Class 5 relay are used for the motors requiring very fast tripping.
| 1.058 * Ir | 1.2 * Ir | 1.5 * Ir | 7.2 * Ir | |
|---|---|---|---|---|
| Class | Time to trip from a cold start | |||
| 10A | >hr | <2hr | <2min | 2s |
| 10 | >2hr | <2hr | <4min | 2s |
| 20 | >2hr | <2hr | 8min | 2s |
| 30 | >2hr | <2hr | <12min | 2s |
As discussed above, there are three major conditions for overload trips:
Apart from these, there may be some additional protection feature available. This varies from one manufacturer to the other.
During normal operation, the current flowing through each pole of an overload relay to the motor remains the same at a time. If anyone of the phase is interrupted, the current through the other two phases rises to 1.73 times the normal value. Hence the overload relay gets heated up and it trips. Phase failure is also known as single phasing of motoror phase loss.
Overload relay cannot protect against short circuits. They should always be used with short circuit protection devices. Otherwise, any short circuits in the motor can potentially damage them. They can protect against overloads, phase loss, and phase imbalance, but not short circuits.
Overload relay is a device that can protect a motor from overloads, phase failure and phase imbalances. Based on the principle of operation they are classified into thermal and electronic overload relay.Thermal OLRis based on the principle of deformation of a bimetallic strip on heating and the electronic overload relay is a microprocessor-based device.
1 - Electronic Overload Relay manufacturer Badha In Manesar
2 - Electronic Overload Relay manufacturer Baghanki In Manesar
3 - Electronic Overload Relay manufacturer Bahora Khurd In Manesar
4 - Electronic Overload Relay manufacturer Bar Gujar In Manesar
5 - Electronic Overload Relay manufacturer Bhudka In Manesar
6 - Electronic Overload Relay manufacturer Bhun Karka In Manesar
7 - Electronic Overload Relay manufacturer Bilaspur In Manesar
8 - Electronic Overload Relay manufacturer Binola In Manesar
9 - Electronic Overload Relay manufacturer Chandla Dungerwas In Manesar
10 - Electronic Overload Relay manufacturer Danokri In Manesar
11 - Electronic Overload Relay manufacturer Darbaripur In Manesar
12 - Electronic Overload Relay manufacturer I.M.T. Chowk In Manesar
13 - Electronic Overload Relay manufacturer Fazalwas In Manesar
14 - Electronic Overload Relay manufacturer Gwaliar In Manesar
15 - Electronic Overload Relay manufacturer Hassanpur In Manesar
16 - Electronic Overload Relay manufacturer Kasan In Manesar
17 - Electronic Overload Relay manufacturer Kherki Manesar
18 - Electronic Overload Relay manufacturer Khoh In Manesar
19 - Electronic Overload Relay manufacturer Kukrola In Manesar
20 - Electronic Overload Relay manufacturer Lakhnola In Manesar
21 - Electronic Overload Relay manufacturer Langra In Manesar
22 - Electronic Overload Relay manufacturer Naharpur Kasan In Manesar
23 - Electronic Overload Relay manufacturer Nainwal In Manesar
24 - Electronic Overload Relay manufacturer Navrangpur In Manesar
25 - Electronic Overload Relay manufacturer Nawada Fatehpur In Manesar
26 - Electronic Overload Relay manufacturer Nurpur Bahora In Manesar
27 - Electronic Overload Relay manufacturer Pathrari In Manesar
28 - Electronic Overload Relay manufacturer Prasoli In Manesar
29 - Electronic Overload Relay manufacturer Rathiwas In Manesar
30 - Electronic Overload Relay manufacturer Sakatpur In Manesar
31 - Electronic Overload Relay manufacturer Sehrawan In Manesar
32 - Electronic Overload Relay manufacturer Shikohpur In Manesar
33 - Electronic Overload Relay manufacturer Sidhrawali In Manesar
34 - Electronic Overload Relay manufacturer Sikanderpur Badha In Manesar
35 - Electronic Overload Relay manufacturer Udepuri In Manesar
