DC Contactors / Disconnects

[Robert1234]

Designing the wiring for the new Magnum inverter, and need to set up for running 200+ amps on the DC side. I like the AMETEK JCY46 & 48 magnetic latching contactors from AMETEK Switch, and am waiting on a price quote. I suspect these may be very high priced options though - maybe too high.

http://www.ametekswitch.com/Products/products.aspx

What other recommendations for contactors / disconnects for the DC side do you have?

[Robert1234]

Lots of views... No reponses? Am I alone in thinking I should have a battery disconnect on the DC side? Is this overkill?

Anyway....

No quote yet, but the vendor did respond. These are the questions that came back to me. Any comments on my answers?

Building a Contactor for a Magnum MS4024PAE inverter.....

Contact Configuration?
Single pole single throw

Contact Voltage?
24v

Contact Current?
166 amp continous
332 amp surge

Load Type, Inductive, Resistive, capacitive?
Inductive

Auxilliary Contacts Required?
No

Coil Voltage?
24v

Coil Duty Cycle?
> 99%. Essentially always on. (Thus the desire for permanent magnetic latching)

Latching Coil?
Preferred

[Sunking]

Robert you are not getting answers because there are only maybe 1 or 2 people who are qualified to answer. I am one of them and do not know enough details to give you an answer. If I did know th edetails there would be a fee associated with it. Sorry but your question is beyond DIY, it is professional and I do not work for free.

[inetdog]

Lots of views... No reponses? Am I alone in thinking I should have a battery disconnect on the DC side? Is this overkill?

Load Type, Inductive, Resistive, capacitive?
Inductive

One of the problems with the DC input of the inverter is that it is not easy to generalize about whether it will show a resistive, capacitive or inductive load to the batteries. A lot will depend on the input filter circuit of the inverter as well as the design of the rest of the circuitry. And for DC, the presence of a net inductive component in the load will cause stress on the switch when it opens under load and a net capacitive component can cause high current as the contacts close from the inverter being off. In either case, the resistive component of the current will also be large. If it is important to the manufacturer of the switch, you need to know the answers to this question, not just provide a guess.

The other questions may not be as obviously problematic, but this one certainly is.

[Sunking]

Contact Current?
166 amp continous
332 amp surge

This is the crux of the problem the manufacture is wanting to know. They want to know what the maximum dead bolted fault current of the system is capable of delivering. That takes a lot of time and calculations of a professional engineer to come up with. What I can tell you it is much higher than 322 amps. Batteries are bad news when it comes to fault current. It can run into 10's of thousands of amps which would weld a 322 amp contactor. Even a small car battery can deliver over 1000 amps easily. This is why I cannot and will not answer. To much is unknown.

[Robert1234]

I can appreciate your positions and responses. A poorly designed contacter can possibly be more hazardous than no contactor at all. DIY at these amperages is certainly not something you just throw together without thorough thought. Making and breaking under load is certainly not intended, but it IS possible that one may wish to break under load in a catastrophic event that doesn't trip the fuse. I'll stay the course working with AMETEK.

[Alden]

Jay 46 contactors

I can appreciate your positions and responses. A poorly designed contacter can possibly be more hazardous than no contactor at all. DIY at these amperages is certainly not something you just throw together without thorough thought. Making and breaking under load is certainly not intended, but it IS possible that one may wish to break under load in a catastrophic event that doesn't trip the fuse. I'll stay the course working with AMETEK.

I have been operating with no disconnect other than bolt cutters (just a fuse). I would think that a fuse would limit any current to the inverter but maybe I am missing some point. I am interested in the Jay 46 contactors and am haven't yet been able to get ahold of an Ametek rep. If you have a source for these units I would be interested.

[Robert1234]

I have been operating with no disconnect other than bolt cutters (just a fuse). I would think that a fuse would limit any current to the inverter but maybe I am missing some point. I am interested in the Jay 46 contactors and am haven't yet been able to get ahold of an Ametek rep. If you have a source for these units I would be interested.

Dave Stewart <Dave.Stewart@ametek.com>

The contactor will be custom designed and built based on your specifications. Expect a price of ~ $80 for a 200+ amp magnetically latching contactor with 4-5 weeks delivery. Kind of a hefty price, but it will last longer than me.

[Alden]

$26 for JAY 46

Joe from Ametek returned my call and quoted me $26 for JAY4604MB00 and $32 for the 150 to 200Amp JBY4603MB00. His number is 585-238-4951. They have a $100 min purchase. He referred me to Tom at J&N auto electric - 5137718000 who sells retails for them. I haven't contacted him yet. I would consider ordering 2 units for me and what ever you want from Ametek, sending you your order and then you paying me if you are interested.

I am planning to build my own control system using a Click PLC and solid state relays (SSR) with extra power going to heat water. I will use the latching contactor for emergency panel isolation and to prevent current back flow at night due the SSRs allowing back flow. These units are just what I was looking for.

[Robert1234]

JCY magnetic latching contactor was the choice for my application. I want to be sure i can break / make connections without arc under full load. Thanks for the offer. I'm good as is.