5 replies to this topic

[sunshine]

Hi gentlemen

We are currently experiening problems starting a 200 kw direct coupled hydralic pump on a 600 kva cont. rated generator. ramped up no load volt to max on genset. . When cold is take at least 2/3 goes to start the motor , the volts drop 25% but the Hz hold up. We burnt one soft starter out.

Would a start delta starter be a better option for this type of load?

The genset appears to be sized correctly & is in good order ( harmonics filter has been fitted to output terminals)

Appreciate any thoughts or ideas


REGARDS


JimP

[Quintono]

Hi JimP,

Firstly a Star/Delta starter for this application will be less forgiving, so I would stick to the Soft Starter (SST).

Have you adjusted any parameters on the SST to suit the Application??
ie.
1) Selected a suitable Start up curve?
2) adjusted the initial voltage setting?
3) changed the current limit from the default setting?
4) on some soft starters there is a pulse start adjustment intended for high friction loads. This usually does the trick in this situation. (When the oil is cold)

It is important to note that the SST has limited amount of starting times per hour. Usually programmable protection function in the Start Up Menu. The norm. is approximately four start per hour under load conditions!
As for burning your SST out, the overload protection function should have picked this up!! What was the fault diagnostic when the fault occured?

Sorry for all the questions.... I am assuming the system voltage is 400V and that the motor has been connection correctly. (As per the Motor nameplate details)

Regards,
Q

[marke]

Hello JimP

Welcome to the forum.

You should not have any difficulty starting that motor on the genset unless the AVR on the genset is playing up, or the soft starter is misfiring, or the start current is too high.

Have you measured the start current during start?
What is the starter type and how is it set up?

What "burnt up" on the failed soft starter?

A star/delta starter is generally far inferior to a soft starter on this type of application due to the switching transient and the high current in delta.
Best regards,

[sunshine]

Hi JimP,

Firstly a Star/Delta starter for this application will be less forgiving, so I would stick to the Soft Starter (SST).

Have you adjusted any parameters on the SST to suit the Application??
ie.
1) Selected a suitable Start up curve?
2) adjusted the initial voltage setting?
3) changed the current limit from the default setting?
4) on some soft starters there is a pulse start adjustment intended for high friction loads. This usually does the trick in this situation. (When the oil is cold)

It is important to note that the SST has limited amount of starting times per hour. Usually programmable protection function in the Start Up Menu. The norm. is approximately four start per hour under load conditions!
As for burning your SST out, the overload protection function should have picked this up!! What was the fault diagnostic when the fault occured?

Sorry for all the questions.... I am assuming the system voltage is 400V and that the motor has been connection correctly. (As per the Motor nameplate details)

Regards,
Q

THANKS Q

For your inteligent response , done Q 1- 4 but done by other so can't directly answer regard inputs.

re- burnt up SST , gave up I guess more to the point. unit replaced was a new Siemens unit using only 2 legs for the soft start. replaced with new 3 legs Nilsen unit. (appears better- maybe just better programming setup ?) System volts adjusted to 440v no load

1 )what about using a immerson heater in the hydraulic tank energised say 10 mins prior to main start

2 ) using the generator as a form of starter to assit the SST by using small manual variac in the genset field circuit to increase the field volts Verses output voltage drops during the
initial start up -with say cut out relay if output voltage exceed 450V during the start/run sequence. The AVR is already attemping to do this, yes.


Regard

JimP

[sunshine]

Hi JimP,

Firstly a Star/Delta starter for this application will be less forgiving, so I would stick to the Soft Starter (SST).

Have you adjusted any parameters on the SST to suit the Application??
ie.
1) Selected a suitable Start up curve?
2) adjusted the initial voltage setting?
3) changed the current limit from the default setting?
4) on some soft starters there is a pulse start adjustment intended for high friction loads. This usually does the trick in this situation. (When the oil is cold)

It is important to note that the SST has limited amount of starting times per hour. Usually programmable protection function in the Start Up Menu. The norm. is approximately four start per hour under load conditions!
As for burning your SST out, the overload protection function should have picked this up!! What was the fault diagnostic when the fault occured?

Sorry for all the questions.... I am assuming the system voltage is 400V and that the motor has been connection correctly. (As per the Motor nameplate details)

Regards,
Q

[Quintono]

Hi JimP,

Regarding question 1) I have installed many a 3 legged soft starter on gen. set applications and only once have had a problem due to cold hydraulic oil. The way I overcame this was to set a pulse start which means applying 80% of nominal voltage for 0.5s, the time is programmable between 0s-2.0s. (all depending on the manufacturers specifications), so I don't think it is necessary to install an immersion heater.

As per question 2) I am not sure, maybe Marke can give us some insight on this...

Regards,
Q