AboutWill Expertise Three phase electic motors, controls and related problems or failures, three phase motor installation issues, performance issues, connections, data and duty cycle information. All other electic motors. Specialty motors, repair concerns, performance concerns, obsolete motors and solutions. Other specialty equipment issues. Lost nameplate data and identification, lost connection data.
Also DC motors of all types.
See my profile under Home/electrical at this site
Experience 30 plus years in the electrical motor and apparatus repair industry. VP level management of repair facilities, current owner of my own specialty repair and consulting firm.
Organizations EASA, IBEW [retired], other specialty organizatons, Lubrication, Vibration EDI, Triboelectric Councils
Publications Currently fielding concerns at this site under "Home Electrical"
Education/Credentials 4 year technical, College level specific courses, EASA repair courses, vibration analysis electronic and electrical trade school.
Expert: Will Date: 6/22/2008 Subject: thermister circuit 230 volt motor
Question hello Will can you give me a brief discription of a thermister circuit and its operating voltage
Answer This is a really involved subject. A true thermistor has nothing to do with the motor operational voltage.
Many times a thermistor is confused with a klixon, which does have voltage considerations.
So lets just deal with the short question, a thermistor is a device, used in motors and other electrical apparatus for monitoring temps internally of the device, however, thermistors can be used to function like a klixon and trip off a device if it should exceed preset temps.
These devices can be buried in the slots of a motor, tied to the end turns in the cooling air stream. buried in transformer windings, the list is endless.
but of all the device and scenarios I have mentioned above, the voltage of the apparatus has no relationship to the thermistor, thermistors are either 10 ohm or 100 platinum or other configuration, the 10 or 100 are most common.
REGARDLESS OF THE MOTOR VOLTAGE. the thermistor is used to monitor temps, set off an alarm, but rarely tied into the control circuit as opposed to klixons, which are bi- metallic temp devices designed to either open or close at a set temp and shut down the motor or other device.
Basically a thermistor is the same thing as implanting a resistor and by change in temperature of the resistor's ambient conditions, the ohmic value changes thus giving a signal that the resistor or thermistor [notice the name], is either changing resistance due to heat or changing resistance due to lack of heat, each ohm might be scaled to 1 degree [really simplistic example].
So if the temp goes up the resistor's value changes with it, and that allows the monitoring.
Again voltage has nothing to do with the resistor, it is only in the change of temp and the not voltage that matters [if we are talking a true thermistor]
