Jump to content

Charger tripping MCB problem


croftie

Featured Posts

I bought a Victron IP22 30 amp charger last summer and sometimes when I switch on (say after return to marina) it momentarily charges at 30amp and trips a 10 amp MCB This is when the MCB has virtually no other load and the batteries are well up toward being fully charged anyway

 

Reset MCB and may be OK, charge starts at 30 amp and drops down as expected over a short period of time. Sometimes takes a couple of goes. I would have thought a 10 amp MCB could cope with a 30 amp charger! If I just connect a 2000w electric fire to that MCB circuit it does not trip so I do not think the problem is the MCB.

 

When the boat was lifted onto the hard in November I purposely applied a load to the batteries (bank of 4 x 110a) to drop SOC a little, prior to turning on the charger. The same thing happened but this time it tripped the marina 10 amp MCB supply instead.

 

Ok so is it a faulty charger or is it just some form of “spike” that chargers can do on start up that is doing the tripping. I have contacted another member on here who has the same 30a charger but has not experienced tripping out on start up.

Link to comment
Share on other sites

Perhaps the MCB has the wrong 'curve'...

I didn't know that MCB have various 'curves' = 'duties' nowadays, perhaps that word  should be replaced by 'sensitivities' in common parlance.

I started this comment with a modicum of tongue in cheek  - but it may well be that electrical installation practice is being pushed towards MCBs tripping 'quicker' on a perceived overload?

Perhaps a more experienced technician could comment?  

Link to comment
Share on other sites

It just sounds to me like the switch-on surge is a bit too much for the 10A MCBs. Phone Onboard Energy and ask if they’ve heard of this before. It’s posdible that it’s a faulty charger although I’d think that unlikely. 

Link to comment
Share on other sites

44 minutes ago, WotEver said:

It just sounds to me like the switch-on surge is a bit too much for the 10A MCBs. Phone Onboard Energy and ask if they’ve heard of this before. It’s posdible that it’s a faulty charger although I’d think that unlikely. 

Thanks

14 minutes ago, Tonka said:

How old is the McB.  Does it have a rcd built in

On the boat typical "garage" consumer unit 1 x RCD 2 x MCB

Age not known

Link to comment
Share on other sites

The Victron innverter/chargers have a substantial iron core transformer. 

It requires a substantial in rush current when switched on. The size of this current and it's decay curve may well be beyond the activation curve of the MCB.

What worked for us was starting the engine, so the engine alternator satisfied the initial charging of the batteries and then after about a minute switching on the shoreline. A bit of load sharing for start up. This procedure even worked for us charging leisure batteries that had been left self discharging for six plus months each winter. 

Good luck

Link to comment
Share on other sites

15 hours ago, DandV said:

The Victron innverter/chargers have a substantial iron core transformer. 

It requires a substantial in rush current when switched on. The size of this current and it's decay curve may well be beyond the activation curve of the MCB.

What worked for us was starting the engine, so the engine alternator satisfied the initial charging of the batteries and then after about a minute switching on the shoreline. A bit of load sharing for start up. This procedure even worked for us charging leisure batteries that had been left self discharging for six plus months each winter. 

Good luck

What I was thinking but not familiar with the Victron device. Our isolation transformer trips the shore MCB about one in four times on connection, depending on at what part of the AC cycle connection is made. Would put in a surge limiter but it's less hassle to go and reset the MCB.

Link to comment
Share on other sites

MCB come in different types - b, c, d curves. Typically b curve types are used in domestic but c curve types  are more suited to fluorescent or motor loads. Might be worth swapping your mcb for a c curve type if you have something with a big transformer in it.

 

They aren’t usually much different in price if not the same. 

Link to comment
Share on other sites

Tipping current for a B   curve is 3 / 5 time the current rating of the MCB

A C curve MCB tip between 5 / 10 the rating of the MCB.

A D curve MCB tip between 10 / 20 the rating of the MCB.

 

I have often found Boat Builders using D  type MCB's,  the cable will melt long before the MCB operates 

Link to comment
Share on other sites

1 hour ago, Keith M said:

Tipping current for a B   curve is 3 / 5 time the current rating of the MCB

A C curve MCB tip between 5 / 10 the rating of the MCB.

A D curve MCB tip between 10 / 20 the rating of the MCB.

 

I have often found Boat Builders using D  type MCB's,  the cable will melt long before the MCB operates 

 

https://info.e-t-a.com/ES-2017-02-IndustrialAutomation-DCurve_LP-Destination.html

 

 

Link to comment
Share on other sites

1 minute ago, Keith M said:

Having quickly scanned the document I cannot see if it for AC or DC circuits, both of which require total different types breakers

Thats because most breakers are used on AC systems.

When I fitted my boat I considered using MCB for DC circuits and (from memory) Schneider breakers are ok to use on DC, though performance curves are adjusted, but in the end I used blade fuses.  So for 12V some breakers are acceptable for use.

Link to comment
Share on other sites

Some Schneider breakers are suitable for DC voltages however they cost is 3 or 4 the cost of an AC breaker.

You will not be able to pick them up from any electrical distributor they will require ordering.

 

Some breakers can only be used with 24 volts DC. 

Link to comment
Share on other sites

8 hours ago, Onewheeler said:

Our isolation transformer trips the shore MCB about one in four times on connection, depending on at what part of the AC cycle connection is made. Would put in a surge limiter but it's less hassle to go and reset the MCB.

Is it an Airlink?  My understanding is that they already incorporate an NTC thermistor specifically to address switch-on surge. 

Link to comment
Share on other sites

1 hour ago, WotEver said:

Is it an Airlink?  My understanding is that they already incorporate an NTC thermistor specifically to address switch-on surge. 

No, it's a generic one from Ebay. Does the job though. I'm hesitant about a thermistor, probably OK but they get hot. I've designed a circuit but have more interesting or urgent things (depending on whether I'm listening to me or her indoors) that get in the way of building it.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.