question

[hesham]

Hard wired

Hi all
Y-D starter shouldn't go through the PLC .specially if the operator have a manual mode of operation .in this mode he definetly should not go through the PLC and use the hard wired interlocks and timers in the same time i agree with the guys who said that it's a sefety issue to use the hard wired interlocks and timer because even the interlocks stucked the operation is still safe.in the same time we will save in PLC I/o's
BR

 

[BobB]

Y-D starter shouldn't go through the PLC .specially if the operator have a manual mode of operation .in this mode he definetly should not go through the PLC and use the hard wired interlocks and timers in the same time i agree with the guys who said that it's a sefety issue to use the hard wired interlocks and timer because even the interlocks stucked the operation is still safe.in the same time we will save in PLC I/o's

Still do not agree. It is really a personal preference. Let's face it, YD starters are only timers and status contacts whether the interlocks are hard wired or performed in software.

It is the same as any other software function. If you foul it up it goes bang. Same goes for hard wired.

The only thing I will not compromise is to have a mechanical interlock between the Y and D contactors, PLC controlled or hard wired.

Strangely enough the 2 most popular off the shelf YD starters sold in Ozz generally do not have mechanical interlocks, only electrical. If a contactor auxiliary contact "sticks", the starter goes bang in the night again. To my mind that is far more dangerous than PLC control with mechanical interlocks.

By the way, the brands are the most popular control equipment and contactors sold in Ozz.

 

[darrenj]

i agree with BobB..As long as it has a mechanical interlock a PLC is a good choice..Lets face it in todays world if a The PLC is down you will not be needing that Y delta motor to start anyway!..(Unless you have stand alone equiptment)

Oh well i guess its personal pref.

But i prefer a PLC to control as much as possible..

 

[AutomaticLeigh]

I still don't see it. If I toddle along to the MCC and select "Hand", I don't expect to need a PLC to start the motor. Also, if I've got a long PLC scan time, I've now got a timing issue to worry about. OK, I can use immediate process update or whatever, but why bother. Put a separate timer in the starter cubicle - job done, one less thing to worry about.

 

[504bloke]

My two penneths worth


I still agree with Bob

 

[BobB]

Also, if I've got a long PLC scan time, I've now got a timing issue to worry about.

What do you mean? The longest scan time I have seen in my PLC of choice in recent years is 10-12 ms. My finger don't work that fast.

Put a separate timer in the starter cubicle - job done, one less thing to worry about.Yesterday 11:07 AM

The timer is far more of a worry than the PLC. Timers are notorious for carking it quite frankly.

 

[PhilipW]

Timers are notorious for carking it quite frankly.

Ah Bob, you gotta stop using those "cark-prone" Omron timers.

 

[BobB]

Ah Bob, you gotta stop using those "cark-prone" Omron timers.

Good one Philip, but I do not use them. The timers I refer to are used by the manufacturers of the YD starters, the same manufacturers as you have in the land of the long white cloud. You know who I mean. They use their own timers of course. Mostly they are very good but I do remember "orange fuses". Do you?

The only timers I use these days are an occassional time clock, Omron ZEN smart relays as 4-6-8 channel time clocks as they are far cheaper than the other ones, and thousands of PLC timers. They in fact are the cheapest of the lot, and the most reliable.

By the way, how is the weather over there? If it raining send us some. Have not had any decent rain for years really.