What are the differences between the two types of thermal overload relays?
What will be an ideal response?
The solder pot-type overload relay works by placing a brass shaft inside a brass tube. A serrated wheel is attached to the brass shaft. Solder is used to bond the brass shaft to the brass tube. A lever arm between the contacts and serrated wheel holds the contacts in place. If the motor current becomes excessive, the heater will melt the solder and permit the serrated wheel to turn, causing the normally closed auxiliary contacts to open. The bimetal strip-type overload uses a bimetal strip to open the normally closed auxiliary contacts if the motor current becomes excessive. There are other differences between the solder pot-type and bimetal strip-type overload relay. Bimetal strip-type overload relays generally permit the trip current to be adjusted to between 85% and 115% of the heater rating. Another difference is that bimetal strip-type overloads can generally be set to permit the contacts to reset automatically or manually after the bimetal strip has cooled sufficiently. Generally, the relay is adjusted for manual reset. Automatic reset should be used only if the sudden starting of a motor will not cause danger to personnel or damage equipment.
You might also like to view...
PROBLEM 3.39 The solid spindle AB has a diameter and is made of a steel with and while sleeve CD is made of a brass with and Determine (a) the largest torque T that can be applied at A if the given allowable stresses are not to be exceeded and if the angle of twist of sleeve CD is not to exceed 0.375?, (b) the corresponding angle through which end A rotates.
A vented disc with directional vanes requires what service precaution?
A) Has to be installed with a directional coating B) Must be installed on the correct side of the vehicle C) Plug the vent opening after installation D) Can be rotated left front to right rear
What can happen to an oxyacetylene torch if it is used with too low a flame?
What will be an ideal response?
When estimating an object that has a(n) ____________________ shape, it may be difficult to obtain the exact measurements, and the weight estimation should be based on the largest dimensions that can be obtained.
Fill in the blank(s) with the appropriate word(s).