Motor trip point

FLA Full-limit amps, or the high-amperage trip point for a motor. 

Also, the motor trips are activated, not by excessive motor temperatures, but by an excessive measured amp load to the motor. This is called the FLA (full limit amp load) point. The FLA point may be increased by perhaps 10%, but this will reduce the motor s operational life. Our motor trips at home are activated not by the measured amp load, but by excessive motor temperatures. 

This setting is only a calculation. The exact thermal curves of the motor and the relay should be available to closely match their characteristics at every point. An ideal relay in this case would be one which, without tripping, will permit two consecutive hot starts, i.e. its characteristic should lie above... 

The explosion was due to a failure to directly measure the property that we wish to know. The temperature point was not measuring the temperature in the reactor but the temperature near the pump. This got hot because the pump was running with a closed suction valve. Similarly, the trip initiator on J2 showed that its motor was energized. It did not prove that there was a flow. 

The amp meter on the motor breaker indicates the amps being pulled by the motor. Next to this meter should be a tag or a penciled number, indicating the full-limit amps (FLA) point for the motor. Above the FLA point, the motor should trip off. Operating the motor substantially above its FLA point will burn up the motor s windings. 

This is not quite true. Whenever we start a pump, the starting torque required to get the pump spinning requires a surge of motor amps. To avoid tripping off the motor on high amps, there is a time delay built into the trip mechanism. This delay permits the amperage load to greatly exceed the FLA point, for up to 15 to 30 s. This is too brief a period in which to overheat the motor. 

In addition to following the load, protective overrides prevent the development of excessively low suction pressures (PIC-02), which could result in drawing oil into the compressor and from overloading the drive motor and thereby tripping the circuit breaker (KWIC). In order to prevent reset windup when the controller output is blocked from affecting the SIC set point, external feedback (EFB) is provided for all three controllers. 

Frequently, a major unit shuts down when a compressor trips off. The cause may be low lube- or seal-oil pressure. The pumps providing the lube- and seal-oil pressure are typically spared (backed up). A steam turbine-driven pump is normally backed up by a motor-driven spare. The motor-driven pump should come on when the lube-oil pressure drops below a preset point. 

For intermittent applications, the initial startup torque is substantially greater than for a continuous operation. Therefore, selection of the drive system and the designed failure point of the shear device must be based on the maximum startup torque of a fully loaded system. If either the drive system or designed failure point is not properly sized, this type of conveyor is prone to chronic failures. The predominant failures are frequent breakage of the shear device and trips of the motor s circuit breaker caused by excessive startup amp loads. 

It is also time to question whether mobility really does demand the minimisation of travel time, which is what motorist organisations inevitably clamour for. Much of the motoring public s concern aronnd travel time is not the qnantnm of time itself, but its unpredictability for a given journey. ° People want to plan departure times efficiently they want reliability in their forecasts, but as Staley and Moore point out, the fifteen mile trip from Santa Monica to downtown LA should take about 20 minutes. .. but (it can take) an hour or longer—each way. Should we not focus on reliable accessibility—the ability to get safely to where we need to go at a time of our own choosing within an acceptable time frame Congestion is more a function of interrupted traffic flow than it is of maximum travel speed. 

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