New contact block design for Emergency Stop devices from Siemens

Posted by on March 31, 2011
This entry is part 9 of 9 in the series Emergency Stop

Emergency Stop

One issue that fre­quently comes up when inspect­ing machin­ery is the con­tact blocks used on emer­gency stop devices. Until now, e-​​stop devices were nor­mally fit­ted with the same con­tact blocks used on other oper­a­tor devices, and in cases where the e-​​stop sys­tem is sin­gle chan­nel, you could lose the con­tact block off the back of the oper­a­tor device and not be able to detect it. Since the latch­ing detent device on the but­ton is part of the but­ton and not part of the con­tact block, the but­ton would appear to latch down nor­mally, but the machine would keep running!

I got a newslet­ter in my email today from Siemens that included the fol­low­ing snip on their new 3SB34 emer­gency stop con­tact block and I though I’d share it with you!

Emergency stop con­tact block with mount­ing monitoring

Siemens E-Stop Contact Block 3SB34

Siemens 3SB34 E-​​Stop Contact Block

It is com­mon prac­tice to equip actu­a­tors such as EMERGENCY STOP with stan­dard con­tact blocks. Now the new 3SB34 con­tact block with mount­ing mon­i­tor­ing from the SIRIUS fam­ily offers increased safety – auto­mat­i­cally mon­i­tor­ing not just the con­nec­tion to the actu­a­tor but also the cor­rect mount­ing on the EMERGENCY STOP. The mon­i­tored con­tact blocks are nor­mally closed con­tact blocks with pos­i­tive open­ing oper­a­tion. If the mount­ing is defec­tive or should it fall off the actu­a­tor, the inno­v­a­tive con­tact block trig­gers an auto­matic shut­down of the machine or plant (safe state). As long as the plant is oper­at­ing, you can be sure that all the nec­es­sary con­tacts are func­tion­ing perfectly.

The advan­tages are obvi­ous:
– Increased safety thanks to the test required for ini­tial com­mis­sion­ing
– Higher plant avail­abil­ity thanks to auto­matic mon­i­tor­ing of the mount­ing
sta­tus dur­ing oper­a­tion (accord­ing to the Machinery Directive)
– Space-​​saving thanks to a com­pact design and small instal­la­tion depth (max. 63 mm)
– Free slots for fur­ther con­tact blocks due to inte­grated mount­ing monitoring

The con­tact block is avail­able in two ver­sions – with screw con­nec­tion 3SB3400-​​0M or with spring-​​loaded con­nec­tion 3SB3403-​​0M.

For fur­ther infor­ma­tion, click here.

Since I don’t sell any kind of con­trol prod­ucts, you’ll have to talk to your local Siemens rep­re­sen­ta­tive to get pric­ing and availability.

If any­one has any expe­ri­ences with these prod­ucts that they would like to share, please leave a comment!

+DougNix is Managing Director and Principal Consultant at Compliance InSight Consulting, Inc. (http://​www​.com​pli​an​cein​sight​.ca) in Kitchener, Ontario, and is Lead Author and Managing Editor of the Machinery Safety 101 blog.

Doug’s work includes teach­ing machin­ery risk assess­ment tech­niques pri­vately and through Conestoga College Institute of Technology and Advanced Learning in Kitchener, Ontario, as well as pro­vid­ing tech­ni­cal ser­vices and train­ing pro­grams to clients related to risk assess­ment, indus­trial machin­ery safety, safety-​​related con­trol sys­tem inte­gra­tion and reli­a­bil­ity, laser safety and reg­u­la­tory conformity.

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12 Comments.

  1. Doug Nix April 19, 2011 at 20:01

    Debra Kolbow,

    We would be happy to include REES prod­ucts in the study. We will be releas­ing the Research Proposal shortly so you can see what we plan to do. After that we can make arrange­ments to get sam­ples from you.

    Thanks for vol­un­teer­ing your prod­ucts for our study!

  2. Debra Kolbow April 19, 2011 at 15:02

    Doug Nix,

    Doug, Would you include REES sam­ples in your study, or are we too late. I can ship sam­ples out to you imme­di­ately. Thanks, Debra Kolbow

  3. Debra Kolbow April 19, 2011 at 14:32

    REES, Inc. also man­u­fac­tures a con­tact block attached to an adapter that opens the NC con­tact if removed from the switch oper­a­tor. This fea­ture is avail­able on both our 22.5mm and 30.5mm oper­a­tors. Check out our web­site at http://​www​.reesinc​.com.

  4. Radek Latus April 5, 2011 at 11:07

    Doug Nix,

    Allen-​​Bradley Rockwell has had self-​​monitoring con­tact blocks since the 800E/​800F lines have been ava­iable in North America(2001, I believe). The 800T had these avail­able even longer. If you do a search for self-​​monitoring con­tact blocks in Google there is a bunch of links to info on the AB con­tact blocks. Also, the 800F self-​​monitoring blocks are not lim­ited to E-​​stop but can be used on other oper­a­tors as well. Part num­ber 800F– X01S.

    • Doug Nix April 5, 2011 at 12:35

      Thanks, Radek! I always appre­ci­ate get­ting feed­back from my read­ers. I have decided to con­duct a study of these prod­ucts. I have requested sam­ples from Rockwell/​A-​​B, Telemecanique, Schneider/​Square-​​D, Jokab, ABB and OMRON. I am draft­ing the study pro­posal now and will make it avail­able through the blog for any­one inter­ested. Once the study is com­plete I will be pub­lish­ing the white paper here as well.

      Thanks for the information!

  5. Doug Nix April 4, 2011 at 12:33

    I have had a lot of feed­back on this post­ing from a lot of dif­fer­ent sources, some from my LinkedIn net­works and from other sources includ­ing this blog and Twitter.

    I have decided to con­duct a study of these com­po­nents to see what each man­u­fac­turer is bring­ing to the mar­ket, and to pub­lish the results through this blog and our com­pany web site. If you rep­re­sent a con­trols com­po­nent man­u­fac­turer and would like your company’s prod­uct included in the study, please con­tact me. The study will begin as soon as I receive sam­ples from each manufacturer.

    I look for­ward to the oppor­tu­nity to get a close look at these impor­tant components!

  6. mundo prevencion - trackback on April 1, 2011 at 03:40
  7. Anthony Kerstens March 31, 2011 at 23:36

    That addresses some­thing that has both­ered me about IEC style but­tons for some time. Of course, Allen Bradley has had the SMCB’s (self mon­i­tor­ing con­tact blocks) for some time now, I believe more than 5 years.

    • Doug Nix April 1, 2011 at 09:11

      Anthony,

      Ok, it sounds like it’s time for some field research, since you and Frank say that at least Rockwell has an equiv­a­lent prod­uct. If any­one else has a favourite prod­uct in this line, please com­ment or email me!

  8. Frank Schrever March 31, 2011 at 21:27

    Hi Doug, this approach is not unique to Siemens and has already been avail­able for years from other man­u­fac­tur­ers. It is a very nec­es­sary adap­tion for panel mounted estops, where the block can fall off (regard­less if it is screwed on or bay­o­net mounted, this can hap­pen) and not be seen. With this approach, the cir­cuit opens imme­di­ately if the con­tact block comes off, a prop­erly designed cat­e­gory 3/​4 con­trol sys­tem will detect the fault and not allow a restart until it is fixed

    • Doug Nix April 1, 2011 at 09:10

      Frank,

      This is the first time I have seen this in North America, which is why I pub­lished the arti­cle. I was aware of some other manufacturer’s ‘emer­gency stop con­tacts’ but they did not pro­vide this func­tion­al­ity. Can yu pro­vide me some point­ers to the com­po­nents from other man­u­fac­tur­ers? Perhaps this would be a good oppor­tu­nity for a com­par­i­son arti­cle… :-)

  9. Sicurezzaonline - trackback on March 31, 2011 at 20:42

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