Thermal Overload Protection Of Generator

Due to such symmetrical distribution when three phase power supply.

Thermal overload protection of generator. The most basic safety scheme of the motor is thermal with load protection which mainly covers the protection of all the above conditions. Generator protection should take into account the importance of the generator and its technical characteristics such as power voltage and earthing arrangement. Generator thermal withstand capability from the generator manufacturer s data. The heat produced by the overload current is utilized to trip the motor circuit.

Refer to figure 1 for graphical representation. Although over current relays negative phase sequence relays and devises for monitoring constant flow are also used to provide a certain degree of thermal overload protection. These are mostly used for protection of low voltage squirrel cage induction motors or dc motors of lower output rating. Schematic diagram of a basic motor control scheme.

A thermal overload relay works on the heat produced by the excessive overload current. The relay shall have high reset ratio and adequate continuous thermal rating. There is one cylindrical stator and a three phase winding is symmetrically distributed in the inner periphery of the stator. To understand the basic principle of thermal overload protection let s examine the schematic diagram of a basic motor control scheme.

Generator over voltage protection 59g. Figure 2 protection schematic for generators over 5 mva. Suitable over voltage relays preferably with volt cycle characteristics shall be provided. Low vacuum protection this protection usually is in the form of a regulator which compares the vacuum against atmospheric pressure it is normally fitted to the generator set above 30 mw.

No one would do that of course because you d sacrifice much of the full generator capacity. Protection against overload using thermal relays. One over current relay shall be provided to initiate an overload alarm. Set overload protection function so that it falls to the left of the generator thermal withstand curve.