If the I²t model provides real protection against motor overheating?

Hello everyone,

Recently faced with shutting down of machine (based on third-party drives), which had a fault sounds like "load overheating". Fortunately the protection system triggered, stopped machine and issued a fail.

As It turned out the usual synchro-motors are equipped with double KTY84 (second one as spare), that surprised me. Of course there are three cables going from motor to Drive.

• main power cable and brake;
  
• cable from encoder;
• cable from KTY;

Just in case went to look at similar machine based on Sinamis drives. There was one cable less on motor.There were only main power cable and encoder on all five motors. Surprise!

As it turned out 1FT7... motors and other synchro-servo are deprived such cheapest thing as KTY84 which worth is equal one dollar at retail.

Having studied that theme some theoretical questions had arisen. Moreover the customer's technicians ask good questions.

I believe that theoretically I²t (digital thermal motor model) works normally under ideal conditions. Because that system based on:

• digital model of Simotics motor only;
• taking of temperatures from output electronical IGBT-keys of Drive and probably from control IC chip.

In cases when motor undergoes external high temperature or suddenly shuts down its cooling system (fan, fluid cooling), that system will not protect the motor from overheating, I think.

Please correct me. If I am wrong.

Tech Team

Also note, that KTY84 was discontinued by the manufacturer and the motors are changed to Pt1000 sensors.

 It doesn't matter  KTY84 or Pt1000, I still can't find its ends around motor. the CU320's X522 terminals are empty.

Looks weirdly! The encoder cable goes straight to X202 bypassing X522 which is used for temperature sensors.

Tech team

please note, that the motor temperature signal is included in the encoder cable!

 Read about that cable (6fx8002-2dc20-1ag0). Found nothing there regarding two wires for T.sensor included or whatever.

Please point me in that string at specifications.

I'm still having doubts about presence of KTY84 or PT1000 inside of servo-motor (1FT7...).

P.S. Chapter 9.5 states that if encoder cable connected, the Drive can take all relevant data of motor from EEPROM which is situated on encoder PB. That's clear!

But where is written list of that data? Whether the current temperature of winding is included?

Cheers

Well done! I've got it. The whole point of that in wonderful Drive-CliQ.

If you did not purchase motor with Drive-CliQ be satisfied with I²t thermal model which can kill youre motor.

Now I have something to reassure the customer.

Cheers