# Power flex 700 and Plc



## MDShunk (Jan 7, 2007)

No. The "safe off relay" accessory (might even come standard on the 700) is the real procedure.


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## tates1882 (Sep 3, 2010)

MDShunk said:


> No. The "safe off relay" accessory (might even come standard on the 700) is the real procedure.



Thanks. 


Sent from my iPhone using electriciantalk.com


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## JRaef (Mar 23, 2009)

Unfortunately, there is no "Safe Torque Off" (STO) option card for the PF700. There is for the PF70, but to get that feature in the PF700, you would have to use a 700S, which is an entirely different drive. If you were to do that, might as well go with a newer PF753, it's going to be less expensive and smaller and has the STO option included as standard, for up to PLe / SIL2 / Cat. 3.

Your only "Safety Relay" option that could be certified using the PF700 would be to have the Safety Relay control a contactor on the output (or two in series depending on the safety level you need). Just opening a control input will not be a certifiable safety control method.


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## tates1882 (Sep 3, 2010)

JRaef said:


> Unfortunately, there is no "Safe Torque Off" (STO) option card for the PF700. There is for the PF70, but to get that feature in the PF700, you would have to use a 700S, which is an entirely different drive. If you were to do that, might as well go with a newer PF753, it's going to be less expensive and smaller and has the STO option included as standard, for up to PLe / SIL2 / Cat. 3. Your only "Safety Relay" option that could be certified using the PF700 would be to have the Safety Relay control a contactor on the output (or two in series depending on the safety level you need). Just opening a control input will not be a certifiable safety control method.


Yes discovered that today. Weird that the pf700 doesn't have that option. So basically the Plc guy is sol. We submitted the cat# for the VFD's 2 months before purchase and they never said anything about having to have a safety rated drive. Specs we were given " Allen Bradley 480v 3phase 125hp, 75hp, 50hp, Ethernet comm modules, 120v control cassettes. We could have choose the 753 but only one other facility uses 753 and every one else 700 so it's easier to find parts in a pinch. TGIF


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## KennyW (Aug 31, 2013)

As a side note, these days, generally 753's are cheaper and have shorter lead times than 700. 

Avoid the 700S like the plague.


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## MDShunk (Jan 7, 2007)

KennyW said:


> As a side note, these days, generally 753's are cheaper and have shorter lead times than 700.
> 
> Avoid the 700S like the plague.


My first exposure to the 700S was to replace a failed TB Woods drive at o'dark-thirty. There was no direct replacement Woods drive to be had at that hour, so the 700S was it. The Woods drive is dirt simple (and attendantly bomb proof). The 700S seemed like it had a million settings. Think I could get this thing to run off a 4-20 with a couple simple parameter changes? Not an effing chance. Took longer to find all the right parameters to get it running than it took to swap out the drive. All this, to agitate a tank of salad dressing.


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## The_Modifier (Oct 24, 2009)

MDShunk said:


> All this, to agitate a tank of salad dressing.


Stupid lazy restaurant employees. :jester::laughing:


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## tates1882 (Sep 3, 2010)

JRaef said:


> Unfortunately, there is no "Safe Torque Off" (STO) option card for the PF700. There is for the PF70, but to get that feature in the PF700, you would have to use a 700S, which is an entirely different drive. If you were to do that, might as well go with a newer PF753, it's going to be less expensive and smaller and has the STO option included as standard, for up to PLe / SIL2 / Cat. 3.
> 
> Your only "Safety Relay" option that could be certified using the PF700 would be to have the Safety Relay control a contactor on the output (or two in series depending on the safety level you need). Just opening a control input will not be a certifiable safety control method.


Im not sure why he wants the vfds tied into the safety circuit, the vfds control non hazardous loads, i.e. exhaust/inlet fans, cheese pumps, vibrating bed, cooling stacks. The hazardous part of the machine is the burner train and its controlled by a separate controller with inter ties with the plc and safety relay. each motor has a local disconnect at the motor and multiply estops around the machine.


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## JRaef (Mar 23, 2009)

tates1882 said:


> Im not sure why he wants the vfds tied into the safety circuit, the vfds control non hazardous loads, i.e. exhaust/inlet fans, cheese pumps, vibrating bed, cooling stacks. The hazardous part of the machine is the burner train and its controlled by a separate controller with inter ties with the plc and safety relay. each motor has a local disconnect at the motor and multiply estops around the machine.


Well, maybe then the intent is NOT for "life safety" on every component of the machine, but he wants to use a Safety Relay because it builds-in a specific Restart procedure. For example if someone opens an access hatch to add ingredients. A Safety Relay will require a specific order of events to take place before they can be re-started. I have seen people use what are called "cascaded" safety relays for that reason. Example: Hatch opens, Safety Relay 1 stops the burner because it is dangerous. But if the burner is stopped, you don't want the inlet fan running and contaminating things with no burner, and if the inlet is stopped, you have to stop the outlet fan to avoid negative pressure. Then if the fans are not running, no point if pumping the cheese and if there is no cheese, you don't need the vibrating bed, etc. By using cascaded safety relays, each one has to be re-started in order, but all tied to the fact that the access hatch has to be closed first. In that case, the individual components may not ALL need to be "safety" evaluated, they are just wanting to turn them off.


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## tates1882 (Sep 3, 2010)

JRaef said:


> Well, maybe then the intent is NOT for "life safety" on every component of the machine, but he wants to use a Safety Relay because it builds-in a specific Restart procedure. For example if someone opens an access hatch to add ingredients. A Safety Relay will require a specific order of events to take place before they can be re-started. I have seen people use what are called "cascaded" safety relays for that reason. Example: Hatch opens, Safety Relay 1 stops the burner because it is dangerous. But if the burner is stopped, you don't want the inlet fan running and contaminating things with no burner, and if the inlet is stopped, you have to stop the outlet fan to avoid negative pressure. Then if the fans are not running, no point if pumping the cheese and if there is no cheese, you don't need the vibrating bed, etc. By using cascaded safety relays, each one has to be re-started in order, but all tied to the fact that the access hatch has to be closed first. In that case, the individual components may not ALL need to be "safety" evaluated, they are just wanting to turn them off.


 got ya. So maybe a better way would be to use the vfd enable circuit and tie it in with the Plc not the Saftey relay. Or have an inter posing relay between the drives and Safety relay


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## IP-EI (Apr 7, 2014)

You guys keep mentioning 753s. I've never encountered one. We went straight from 700s to 755s here. Why do you recommend the 53 over the 55? Only issue I have with the 55s is that they are load as hell. 

I have 7 of them in one of my MCCs and you almost have to wear earplugs in there.


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## tates1882 (Sep 3, 2010)

IP-EI said:


> You guys keep mentioning 753s. I've never encountered one. We went straight from 700s to 755s here. Why do you recommend the 53 over the 55? Only issue I have with the 55s is that they are load as hell.
> 
> I have 7 of them in one of my MCCs and you almost have to wear earplugs in there.


Personally I like the 700, it tried true and common for my area. We actually use more Yaskawa then ab. If its a real budget job we use Dura Pulse.


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## JRaef (Mar 23, 2009)

IP-EI said:


> You guys keep mentioning 753s. I've never encountered one. We went straight from 700s to 755s here. Why do you recommend the 53 over the 55? Only issue I have with the 55s is that they are load as hell.
> 
> I have 7 of them in one of my MCCs and you almost have to wear earplugs in there.


753's and 755s are basically the same drive, the 753 has 3 expansion slots, the 755 has 5 expansion slots, hence the 3 and the 5.

But also the 755 has built-in Ethernet, so if you are doing all of the control via Ethernet, as in an Ethernet MCC, then you are better off using a 755. But the 755 does NOT come with any hard-wire I/O on it, you have to add I/O cards if you want that. The 753 has built-in I/O, and if you are using some other comm network beside Ethernet, then you have to buy a comm card for either one, so no point if spending extra for the 755.

Once you go over 350HP though, there is only the 755.


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