Pin/Sleeve Question

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Kobe85

Member
Location
New York
I have a generator that will be connected to a motor control center (MCC) on a movable trailer.

In case the generator goes down, my customer wants to unplug the generator and connect a secondary source of power.

My plan is as follows:
-Type TC cable coming out of the generator in a cord grip run in tray; FYI the generator is in its own enclosure
-On the cable end that will connect to the MCC, the cable will have a connector (female since it could have active power)
-The MCC will have an inlet (male) where the connector attaches since it cannot generate its own power.
-A large danger sign/phenolic will be placed at the MCC inlet warning of turning off the generator before disconnecting.

Eaton pin/sleeves I will be using
http://www.cooperindustries.com/con...cts/documents/brochures/PinSleeveBrochure.pdf

Can anyone suggest if I am violating any safety codes anywhere? I would like to get away without using a safety disconnect if I do not have to ($$$$); that's where I'm hoping the sign/phenolic are acceptable.
 

qcroanoke

Sometimes I don't know if I'm the boxer or the bag
Location
Roanoke, VA.
Occupation
Sorta retired........
I have a generator that will be connected to a motor control center (MCC) on a movable trailer.

In case the generator goes down, my customer wants to unplug the generator and connect a secondary source of power.

My plan is as follows:
-Type TC cable coming out of the generator in a cord grip run in tray; FYI the generator is in its own enclosure
-On the cable end that will connect to the MCC, the cable will have a connector (female since it could have active power)
-The MCC will have an inlet (male) where the connector attaches since it cannot generate its own power.
-A large danger sign/phenolic will be placed at the MCC inlet warning of turning off the generator before disconnecting.

Eaton pin/sleeves I will be using
http://www.cooperindustries.com/con...cts/documents/brochures/PinSleeveBrochure.pdf

Can anyone suggest if I am violating any safety codes anywhere? I would like to get away without using a safety disconnect if I do not have to ($$$$); that's where I'm hoping the sign/phenolic are acceptable.
Is there a transfer switch in this setup? If not it's illegal. You run the risk of back feeding onto the grid without one.
 

kwired

Electron manager
Location
NE Nebraska
I have a generator that will be connected to a motor control center (MCC) on a movable trailer.

In case the generator goes down, my customer wants to unplug the generator and connect a secondary source of power.

My plan is as follows:
-Type TC cable coming out of the generator in a cord grip run in tray; FYI the generator is in its own enclosure
-On the cable end that will connect to the MCC, the cable will have a connector (female since it could have active power)
-The MCC will have an inlet (male) where the connector attaches since it cannot generate its own power.
-A large danger sign/phenolic will be placed at the MCC inlet warning of turning off the generator before disconnecting.

Eaton pin/sleeves I will be using
http://www.cooperindustries.com/con...cts/documents/brochures/PinSleeveBrochure.pdf

Can anyone suggest if I am violating any safety codes anywhere? I would like to get away without using a safety disconnect if I do not have to ($$$$); that's where I'm hoping the sign/phenolic are acceptable.

Regardless of what codes may say I would want to at least see some kind of physical action needed to isolate one source and to connect the other source - and should be complex enough it isn't easy to overlook it and energize both at same time.

I've backfed things before without a transfer switch - and when power comes back on nearly forgetting to disconnect the generator before switching the utility main back on. That got me to thinking when in a makeshift situation to at least disable the utility supply so it can not accidentally be turned on.

If you can't tolerate people needing to physically disable the sources when switching then you need mechanical interlocking system to prevent turning both on at same time - AKA a transfer switch. Kirk key systems also are a variation that works.
 

Kobe85

Member
Location
New York
Thanks for the replies.

My answers-
There is no transfer switch and we don't need one because our generator's connection and the customer's backup connection will not be attached to the MCC at the same time. If the generator goes down, they will disconnect the generator cable from the MCC (using pin/sleeve hookups), and hookup their cable to the MCC connector (same one we used for generator).

If you are having trouble imagining this installation, its a flat bed trailer that will be moved from site to site.

So the TC cable from the generator to the MCC is not portable; it's always connected and powered. The trailer is stand alone and should always work as such. The customer attaching their cable only happens in a "rare" event where the generator shuts down.
 

qcroanoke

Sometimes I don't know if I'm the boxer or the bag
Location
Roanoke, VA.
Occupation
Sorta retired........
Thanks for the replies.

My answers-
There is no transfer switch and we don't need one because our generator's connection and the customer's backup connection will not be attached to the MCC at the same time. If the generator goes down, they will disconnect the generator cable from the MCC (using pin/sleeve hookups), and hookup their cable to the MCC connector (same one we used for generator).

If you are having trouble imagining this installation, its a flat bed trailer that will be moved from site to site.

So the TC cable from the generator to the MCC is not portable; it's always connected and powered. The trailer is stand alone and should always work as such. The customer attaching their cable only happens in a "rare" event where the generator shuts down.

So you're just swapping feeds? There is no utility connection involved? Sort of like feeding it from a different circuit?
I see no problem other than making the connection under load, I wouldn't want to be the one doing it.
 

Kobe85

Member
Location
New York
So you're just swapping feeds? There is no utility connection involved? Sort of like feeding it from a different circuit?
I see no problem other than making the connection under load, I wouldn't want to be the one doing it.

Correct, swapping feeds. Correct signage and proper training will save a $1200 or so safety disconnect.

And will not be disconnected under load, as long as properly done.
 

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
I would avoid calling the connection a disconnect; otherwise, you will need to consider the implications of Section 430.108.
 

kwired

Electron manager
Location
NE Nebraska
You are swapping feeds, yet you have a chance of having two feeds connected simultaneously?

Why not one supply cord/cable with plug on it and plug it into whichever source is going to be used? Then there is no need for signs and proper transfer procedures.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
There is no possibility to connect both sources at once.
The OP's concern is that someone might connect or disconnect the pins under load.
In addition to load break arc issues there could be transient plan neutral or single phasing.
 

kwired

Electron manager
Location
NE Nebraska
There is no possibility to connect both sources at once.
The OP's concern is that someone might connect or disconnect the pins under load.
In addition to load break arc issues there could be transient plan neutral or single phasing.

If that is the case what is wrong with a sign that says do not plug/unplug under load? You can keep it simple or make it complicated - average production employee will ignore it either way:)
 

Smart $

Esteemed Member
Location
Ohio
If that is the case what is wrong with a sign that says do not plug/unplug under load? You can keep it simple or make it complicated - average production employee will ignore it either way:)
I seem to recall that a disconnect switch is required for pin/sleeve connectors not listed to be disconnected under load... but it is a faint recollection that may not hold any truth. Will investigate as time permits, but one of y'all may confirm or disprove before I get to it...
 

Smart $

Esteemed Member
Location
Ohio
I seem to recall that a disconnect switch is required for pin/sleeve connectors not listed to be disconnected under load... but it is a faint recollection that may not hold any truth. Will investigate as time permits, but one of y'all may confirm or disprove before I get to it...
Couldn't confirm on quick search... but got to thinking that he's powering an MCC. Does this MCC have a main switch? If direct connect to the MCC bus, Code does not permit more than 6 grouped disconnects off of that bus. If it has a main and the generator has a breaker (or other means of disconnect) no additional disconnect would be necessary even if a disconnect for a do-not-disconnect-under-load connector is used.

OP: Have you looked into a connector pair that is rated for disconnect under load?
 

kwired

Electron manager
Location
NE Nebraska
Connecting/disconnecting under load isn't exactly same thing as connecting/disconnecting while energized with no load - but is still wise to do non- energized in most cases.
 

Kobe85

Member
Location
New York
Couldn't confirm on quick search... but got to thinking that he's powering an MCC. Does this MCC have a main switch? If direct connect to the MCC bus, Code does not permit more than 6 grouped disconnects off of that bus. If it has a main and the generator has a breaker (or other means of disconnect) no additional disconnect would be necessary even if a disconnect for a do-not-disconnect-under-load connector is used.

OP: Have you looked into a connector pair that is rated for disconnect under load?

Briefly. But, it's something I want to avoid seeing the scenario where it could happen is a) where people ignore training or b) the generator has failed.
This is a million dollar operation so it is "unlikely" that the trained personnel will be lacking many skills, but that's my customer's problem.

If the generator has failed, the chance of disconnecting it under load is also very unlikely
 

Kobe85

Member
Location
New York
You said you where putting a plug on the TC cable, that means you are trying to use it as portable cord

So is there anyway for me to avoid this? If its a "portable" cord than I am required to use a type SOOW or similar?

The distance of this cable run in tray is less than ten feet.
 

Kobe85

Member
Location
New York
Maybe I haven't been clear, but the generator and associated skid here are not separate. They are both together and the generator cannot be removed from the skid; the generator is not portable.

The design is that the generator will always be connected. Upon a catastrophic failure where the generator is broken or fails, it is removed through these connectors and the connectors allow the customer to hook up nearby power (without internal enclosure wiring) without losing any days of work while awaiting a generator fix
 

Smart $

Esteemed Member
Location
Ohio
Briefly. But, it's something I want to avoid seeing the scenario where it could happen is a) where people ignore training or b) the generator has failed.
This is a million dollar operation so it is "unlikely" that the trained personnel will be lacking many skills, but that's my customer's problem.

If the generator has failed, the chance of disconnecting it under load is also very unlikely
Aye... but you are suggesting that an alternate source will be plugged into the same MCC "socket". Connecting under load has similar dangers to disconnecting under load (even more so when safe switching procedures are necessary)... so you'd want your "socket" to be rated for disconnect under load, unless you have an automated protective element to prevent connection under load.

JMO
 
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