6RA70 Thyristor check

Hello Experts,

                         we have on 6RA7097-4KS22 mill stand drive,

when we measure drive incoming R, Y, B current  there is 100 amp difference between two phases,

R=860, Y=810, B=920 Amp,  (we measure this because we are observing problem in its incoming transformer 11kv/700v primary tripped once)

i have attached this drive Trace-2 file,

pls check and tell all thyristor are firing properly,

how to check all THYRISTOR Firing properly ? (which is better P830  or U840 -give further idea on this)

if one thyristor will not fire what is symptoms (what type of problem will occur).

Thanks & Regards,

Meet

Hello Meet

You can Run Thyristor check using Control Word P830  = 3  However please note the conditions underwhich this can be done.

You can also Manually check the healthiness of the thyristors as described in the following FAQ :

https://support.industry.siemens.com/cs/in/en/view/50575033

Hope this helps

Cheers

Navnag

Hi Meet

You can check the Current feed back waveform. For a healthy 1Q drive you should get 6 pulses of equal amplitude as a rectified DC.

Regards,

Vijay

Thanks Navang & Vijay,

                          we have check thyristor test and its details as attached document (6RA70 Thyristor doubt.pdf) ,

in addition i have attached (6RA70 FIRING.pdf), where we can see this problematic drive Current six pulse is not similar as normal drive.

we have changed CUD-1, Power interface etc, 

please guide further what can be done.

Regards,

Meet

Hi to all,

           above problem solved, there was problem in incoming power transformer (tap switch faulty).

Regards,

Meet