Starter Ratings to IEC60947-4-2
Posted 28 November 2002 - 06:04 AM
As it has been a long time since my last post or response, I thought I might ask a couple of questions that may generate some interest and on-going discussion. These relate to starter ratings presentied in the format described by IEC60947-4-2.
Consider the following example.
125A: AC53a: 3.5 - 10: 70 - 10
125A implies starter rating expressed in Amps
AC53a implies starter is suitable for driving a squirrel cage motor and that the amps rating is based on continuous (non-bypassed) operation.
3.5 - 10 implies a maximum starting current of 3.5 x starter amps for a period not exceeding 10 seconds.
70 - 10 implies an on-load factor of 70% and 10 starts per hour equally spaced.
My questions are as follows:
1. Assuming we are able to start the driven machine within 5 seconds at a starting current not exceeding 3.5 time the starter rating, can we achieve 20 starts per hour (equally spaced and at 70% on-load factor) without compromising starter service life?
2. An on load factor of 70% and 10 starts per hour equally spaced implies a period of 350 seconds between completion of 1 start (ramp) and commencement of the next. What is the affect on starter ratings if the soft stop function is enabled?
I look forward to your responses.
Posted 18 August 2003 - 07:02 AM
Posted 12 November 2004 - 07:03 AM
Posted 12 November 2004 - 07:16 AM
Breakdown of IEC 60947-4-2 is as follows;
IEC 60947 is the standard applicable to Low-voltage Switchgear & Controlgear.
Part 4 of that standard relates to contactors and motor-starters.
Section 2 relates to AC Semiconductor motor controllers and starters.
Hope this helps.
Posted 13 November 2004 - 04:25 AM
Thanks for the info but I need details of all sub-clauses, eg. for AC Drive EMC test IEC-61800-3, there are a few tests such as ESD, THD, conducted and radiated immunity, surge etc....If I remember correctly, there are about 7 or 8 tests altogether but for IEC/EN60947-4-2, how many are there?
I tried to check from our local test lab and most of them do not know details about this test. Pls can you tell me what are they? I need to look for a lab who can conduct tests required for IEC/EN60947-4-2.
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