Increasing The Time Of Locked Rotor Current Value On A Cet5

Hello again

A question, EOL CET 5, tripping on locked rotor current only startups, whether pump has been off for 10 minutes or 24 hours.
Total number of pumps that have had there EOL changed from CET3's to CET5's is 4.
The CET 5's where set at the factory settings of 6 FLA at 10 secs
The motor locked rotor current is 7.5 FLA. application is a slurry centrifugal pump.
We have worked out how to gain access to level 2 and change the FLC to 8 times the only thing is due to the trip curve 5 secs is all we can achieve.
This is the question the acceleration factor TD equals 1?
Changing this constant which way up or down to a max of 1.5 or down to say 0.5, does this increase or decrease the desired time of say 10 to 15 secs to allow the pump to start under load.

Regards

PhilD

Asynchronous Induction Motor

Application is a rotary breaker employing a 110kw 1485 rpm 180 amp motor which was a pope motor which is no longer made in Australia.
We need a replacement motor with a no load current of 28.6 amps, as the rotary breakers employs a control loop using the motor current to control the feed rate. The lower the NLA the better, as at present the motor is running at 70 amps with the breaker empty and the setpoint is 130 amps which slows the feeder down if the current exceeds the setpoint and at 170 amps stops the feeder.
The feed is been restricted to 800 TPH instead of 1500 TPH
They replaced the motor with another brand and what I have discovered is nearly all the current motor manufactures have a no load current in the 50 to 60 amp range for a 110kw motor.
For the time being we have doctored the current readings from the motor into the plc to allow higher feed rates into the breaker. Running the risk of bogging the breaker.
So if anyone can tell me of a motor that fits the bill.

PhilD

Failures of poor design

Hello

Again I'm writing to you all again.
An existing substation with a new fugi frenic 5000 variable drive with a 120mm2 Varolex screened power cable, the screen is earthed with hose clamps with tails attached to the earths at both ends @ 400 meters in lengh to a standard 132 kw asychronous induction motor driving a conveyor to a rock reject bin.
This plant has been in existence for 6 months.
In that time, all the 500ma earth leakage protection namely the EL1 and EL2 in the substation at sometime has tripped randomly. The CT's for the MCC monitor the main neutral back to 11kv/415v transformer. As well, all the substation feeder supplies earth leakage protection in the vicinity also trip.
The VSD has a line filter, but has no filter on the output to the motor cable.
Recently the Toshiba 132kw motor failed with an earth fault
Words like parasitic currents, motor terminal over voltage, dv/dt, voltage reflection and inverter rated motors all come in to play. As well as 5% impedance load reactors , Sine Wave Filters and snubbers fitted at the motor to try minimise the problem of a long cable run.
My employer is playing hard ball with the contractors with the construction issues, not so much with the operational issues as outlined.
I'm not going into the politics or issues outlined, if anyone can suggest a direction to take it would be appeciated by waa, as i'm just a humble person who unfortunatly has been lumbered with the problem when at work, which is usually at night time.

Regards

PhilD

Two motors burnout in two weeks

As stated two 132kw motors burn't out in two weeks on conveyor. Last motor suffered bearing failure and severe meltdown.
Protection is CET3 and Siemens thermistor relay at MCC.
Checked settings on CET3 at rated current of motor, tripping time 10 secs. thermistor cct 260 ohms at 22 C.
Changed CET3 on suspicion as no real way checking EOL for overload operation, thermistor relay did operate with o/c of thermistor cct.
Cannot find any info for S+S CET3 on net, we are slowly replacing the CET3 with CET4's throughout the plant.
Until that happens we are stuck with the CET3's, so if anyone can shine some light on CET3 it would be appreciated.

Regards

PhilD

sprecher + schuh CET4 Overload

Hello

Does anyone know of how to change the analogue output through the menu to be used as motor current reading to a PLC from a CET4.
From what I have read 100 % equals 12 mA.
I have had a look through the setup and can't see the parameter to enable or disable.


There are three possibilities.

Analog output motor current
Analog output therm. utilisation
Analog output PT 100 temperature.
Somewhere in the manual probably will be the answer, so hopefully someone may have had the pleasure.

regards

Phild