مصدر : mepca الهندسة
VACON المملكة المتحدة – باستخدام محركات متغيرة السرعة (VSDs) هو وسيلة رائعة لتوفير الطاقة ولكن, إذا VSDs الخاصة بك أكثر من خمس سنوات من العمر, حان الوقت لإلقاء نظرة أخرى على منهم, يقول ستيفن تخار, المدير التنفيذي لميلان متغير سرعة محرك خبير, VACON المملكة المتحدة.
على مدى العقد الماضي, وكانت الصحافة الفنية تعج قصص عن وفورات الطاقة التي يمكن أن تقدمها VSDs المناسب. قصص صحيحة, وهذا هو السبب العديد من الشركات بالفعل بتثبيت VSDs. عندما المهندسين في هذه الشركات رؤية الطاقة VSD إنقاذ قصص, انهم ربما يعتقدون أنهم كنت هناك، وفعلت ذلك, ولكن هم ما يبرره في الجلوس والاستمتاع وهج العمل بصورة جيدة? التي تعتمد على عمر VSDs بهم. لو انهم فقط بضع سنوات من العمر, فمن غير المرجح أن هناك حاجة إلى مزيد من العمل. ولكن إذا كان VSDs أكثر من خمس سنوات من العمر, انها قصة مختلفة.
That’s because the intrinsic efficiency of VSDs has improved considerably in recent years. It’s not, لكن, as simple as saying that VSD efficiency has improved by one or two per cent over the full operating range, because the efficiency improvements relate mostly to operation at reduced loads and speeds.
The efficiency of older drives running at less than 50% load can be surprisingly low – many small drives over five years old struggle to reach 60% efficiency at 40% حمولة. The larger drives of the era fare somewhat better, but even with them, 80% efficiency at 40% load would have been considered satisfactory. In contrast, the latest ac VSDs deliver at least 90% efficiency down to 20% of full load.
But does this extra efficiency matter? After all, the gains are biggest when the drives are lightly loaded, and how often does that happen? In many applications, the answer is that the drives run lightly loaded most of the time.
Designers size motors for worst-case conditions – with an air-conditioning installation, مثلا, this would be the hottest day of the year. Then they further increase the motor size “to be on the safe side”. This means most fan and pump motors rarely need to deliver full output. Instead, they spend their lives running lightly loaded, which is the least efficient area of operation for older VSDs. This is a very good reason to review the efficiency of older VSDs and, if necessary, replace them with modern products.
And it’s not only efficiency that will be improved by installing new drives. The latest units are much more reliable and, in today’s de-skilled world, this is a very real advantage. وبالإضافة إلى ذلك, modern VSDs have superior harmonic and EMC performance, making it easier for users to satisfy the demands of the supply authorities.
There’s no doubt that, in appropriate applications, VSDs deliver big energy savings but older VSDs aren’t a “fit-and-forget” solution. They probably did a great job in their day, but it’s likely that they are now markedly inferior to the latest products. باختصار, if your VSDs have passed their fifth birthday, it’s time to talk to an expert like Vacon about reviewing their performance. You may be pleasantly surprised at the savings you could make!
مصدر : mepca الهندسة