Common Field E-Stop for multiple motors 1

[Histor]

Hi,
Please help me on how can I use common Field E-Stop button for multiple motors?

There are around 9 motors in the package which needs to be wired to one EStop at field. In Motor control center panel, all these 9 motors has individual DOL Starter circuits as attached. But now I would like to use a common E-Stop instead individual EStops. How Can I easily fix this issue?

Thanks.

 

[che12345]

Mr Histor (Electrical)(OP)8 Apr 23 05:25
" .... how can I use common Field E-Stop button for multiple motors? There are around 9 motors in the package which needs to be wired to one EStop at field. In Motor control center panel, all these 9 motors has individual DOL Starter circuits as attached. But now I would like to use a common E-Stop instead individual EStops. How Can I easily fix this issue? "
1. I noticed that there are numerous mistakes/errors to look into:
(a) L1, L2, L3 and N are reversed,
(b) All breakers Qxx shall be 3-pole. N-pole shall not be used for L3,
(c) All main contactors KMxx shall be 3-pole. Auxiliary contact shall not be used for L3,
(d) M2 is wrong. Should be M1 etc., also on the others,
(e) to add a Stop push-button in the MCC instead of using E-stop as a Stop,
(f) there are other errors ........
2. There are E-stop push-button on the market that can stack/add on more contact block with NC contacts.
2.1 Replace the existing E-stops in the MCC by the field single E-stop push-button NC contact....

Che Kuan Yau (Singapore).

 

[waross]

Has the drawing been changed?
I don't see the issues that Mr. Che mentions.
Based on field experience and possible failures if four or nine contact blocks are stacked on one push button;
I suggest three 4 pole control relays.
Each relay will used one pole for self-sealing and three poles for shutting down motors.
One push button may energize all three relays which will then seal in.
One push button (The E stop) will drop out all three relays.
There are several places in your wiring schemes where the added relay contacts may be inserted to shut down the motors.
I strongly advise to use standard, off the shelf, components rather than trying to source a nine pole device.
Part of designing control schemes is anticipating possible failure modes and the availability of replacement parts.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[BrianPetersen]

An emergency-stop in my world (industrial automation) is part of a safety system. Safety relays are available which integrate the stop and manual-reset functions, and expansion relays are available to slave a safety output to many other output circuits. Phoenix Contact, AllenBradley, Pilz, and many others have such components available. It will typically be necessary for such components to be in their own separate master control panel with 24-volt DC power supply and so forth. Depending on the application, it may not be sufficient to use a single means of interrupting the mains power supply - it may require redundant contacts. Establishing this, depends upon a risk assessment. In my world, that involves ISO 13849-1.

Safety functions have to be specially designed; it is not "hard" but for someone who has not been involved with this before, I would suggest having someone experienced do this design (in accordance with applicable standards) while you watch for next time.

 

[moa1]

Possibly a field operated shunt-trip mechanism ahead of your multi motor package.
Good Luck

 

[waross]

In some areas, shunt trip implies power to trip.
That is not fail safe for an E-Stop.
Another thought.
When a large number of devices must be simultaneously disconnected, a main power contactor in the main supply may be used.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[che12345]

Mr Histor (Electrical)(OP)8 Apr 23 05:25
Further to my earlier mail dated 8th instant, I would like to point out the other flaws as following:
(a) Why the motors are without thermal over-load protection ? Are the breakers Qx MPC with breaking capacity and the overload tripping has a thermal say Class 10 or 10A ...... thermal tripping characteristic?,
(b) Any special reasons why requires AC 230V and DC 24V control circuits? Can the DC circuit be replaced by AC with a step-down control transformer to the required low < 230V ?
(c) Why the AC and DC control circuits are not short-circuit protected with fuse/breaker ?
(d) Why use individual battery without charger , instead of a single battery with charger?
(e) Are there going to have (9pcs of individual) E-stop on the MCC single panel door? If all the starters are housed in a single MCC, replace them with one and only one; unless the starters are located at different locations,
Che Kuan Yau (Singapore)

 

[FacEngrPE]

Under NFPA 79, you could specify either of these, providing you understand which one results in acceptably low risk.

Emergency ‘Off’
‘Emergency off’ focuses on the procedure to quickly and safely shut off power to a machine or system in the event of an emergency.
Emergency ‘Stop’
‘Emergency stop’ focuses on the procedure to quickly and safely shut down a machine or system in the event of an emergency.

The major providers of MCC's offer guidance regarding offered safety subsystems. The requirements are more than just replacing stop buttons with big red mushroom buttons.

https://www.rockwellautomation.com/.../technical/motor-control/low-voltage-mcc.html

Functional Safety Application

https://literature.rockwellautomation.com/idc/groups/literature/documents/at/mcc-at007_-en-p.pdf