Dear S.M. Umarye,

Whether your equipment is subject to the IEC 60204 standard or other standards, none of the standards will allow fuses to be blown.

Also the OEM cannot stay in business with selling not functioning equipment.

As any malfunctioning in equipment, you will have to investigate the intended working and the cause of the problem.

-Is the combination of components right?. (a too big drive and a too small Volt-Herz regulator). Check the design and how the installation is operated.

-Are the settings right

-As the problem is in the regenerative mode, is the regenerative energy dissipated in a too short period of time.

-Install monitoring equipment on the equipment and operate until the defects show.

Then it is possible to reconstruct the sequence of events and sort out the cause.

Of course this procedure requires the input of a skilled electrical engineer and the full cooperation of the OEM and the electrical diagrams

A fuse blows at too high currents and when they do that, when even not in use, you should also check the quality of your wiring and may be also for unknown command signals.

It could also be a matter of guarantee.

success ■

Hi Mr. Umarye,

The fuse blowing on cranes , is a typical problem observed in the 4-Q Thyristorised rectifier AC drives or Thyristorised DC drives , during regeneration , whenever fed from a weak power supply.

Thyristors are line commutated devices and they cannot turn off their own current. For unstable power supply , proper thyristor commutation cannot be ensured and the fuses blow in order to protect the thyristors.

The blowing of the fuses should not be treated as a problem but as a protection for the thyristors against the weak supply.

Normally an auto transformer should be used to increase the i/p voltage to increase the margin of safe commutation. However any voltage dip beyond 10-20% will result in fuse blowing issues.

Permanent remedy can be use of IGBT based incomer units , which has becopme popular during the last 5-6 years . IGBTs are self commutated devices and do not depend on the line supply for shutting down. However you have to ensure proper motor insulation material to take care of the higher peaks that can arise due to the use of these devices. (otherwise there will be motor failures)

How stable is your grid voltage?

Regarding the standards - IEC 60204 , Part 32( more specific) is the international standard followed world-wide for crane operation & safety aspects . Any standard mentions the basic guidelines which is followed by OEMs , Consultants and End Users.

I have never come across SEMI F47 in the crane industry. cannot really comment.

Thanks ■

I have seen 6 fuses in our plant UPS system fail this year. Each has been on a low current circuit. There has been no good explanation by the manufacturer except to say that there might be a service life of about 5 years associated with these fuses that range in 15, 20, 25, and 30 amps. We have tested inspected the installation of our UPS and do not believe the problem lies there or with the wiring of the field devices. ■