Looking for an Electromechanical Device kind of Relay / Shunt Trip Unit

[silverstone]

I hope some of you might know the name of such a device, assuming it exists.

What I am looking for is some kind of "shunt trip unit" Relay that, when energized (say 24VDC or 230VAC) "latches" and disconnects power (contacts configuration change from COM-NO to COM-NC).

I would just like a "Relay" that, when energized, trip its associated circuit, REQUIRING a MANUAL RESET of some sorts (preferrably just a lever). Basically without a breaker.

Bistable relays are close, but the ones with dual coil are expensive and, realistically, SET and RESET coils can be interchanged most of the time. This means that in case of a software bug, nothing prevents the system from being re-energized.

Multifunction Timer Relay are also close, and one could say that with a big enough delay after a pulse, it's ALMOST a manual reset (e.g. delay of the order of DAYS after a pulse is applied).

Shunt trip unit + breaker powering some kind of intermediate circuit that is then fed to the application, would be yet another alternative. But since SEVERAL circuits are needed, this becomes quickly expensive and large in terms of surface area.

I also considered buying some cheap chinese trip units such as CHINT off Aliexpress for instance:

https://www.aliexpress.com/item/1005003930733432.html?spm=a2g0o.productlist.main.5.693322c3g62tDm&algo_pvid=9899f251-cad8-48c5-a459-1927c022c310&algo_exp_id=9899f251-cad8-48c5-a459-1927c022c310-2&pdp_npi=4%40dis%21USD%213.12%212.65%21%21%213.12%21%21%40210318b816955738520362691e85a7%2112000031467106874%21sea%21DK%211759269695%21&curPageLogUid=0CwhX7iuB1dC

Do you know if such a "single shot" triggered device exist and what name it has ?

 

[mikefitz]

The Complete Guide To Latching Relays | RS

ie.rs-online.com

 

[timselectric]

I'm not exactly sure what you are trying to do.
But possibly a motor starter and control relay is what you need.

 

[silverstone]

I'm not exactly sure what you are trying to do.
But possibly a motor starter and control relay is what you need.

Safety chain for e.g. smoke detectors. Prevent inadverten turn-on again due to e.g. software bug or smoke alarm self-resetting itself (the relay of the smoke detector is NON-Latching).

 

[silverstone]

The Complete Guide To Latching Relays | RS

ie.rs-online.com

But they are all "self-resetting" if another pulse (on a different contact or of a different polarity) is sent to the relay .

 

[timselectric]

So, it sounds like you need a low power solution. In a small form factor. To be able to incorporate it into a smoke detector.

Doesn’t sound solar related. But, good luck.

 

[silverstone]

So, it sounds like you need a low power solution. In a small form factor. To be able to incorporate it into a smoke detector.

Doesn’t sound solar related. But, good luck.

Not to be incorporated into a smoke detector ... That was an example of an application.

Like I have my smoke detector go off -> trigger a relay to permanently cut power from my contactor coil etc.

 

[timselectric]

Power one side of the contactor coil from the load side of the contactor.
When it's on, it keeps itself on.
The trigger releases it. And a bypass push button resets it.

 

[silverstone]

Power the contactor coil from the load side of the contactor.
When it's on, it keeps itself on.
The trigger releases it. And a bypass push button resets it.

While it wouldn't cover the case where there is a temporary power failure (NOT a wanted trip) but actually it's not a bad idea, thanks for the tip .

 

[timselectric]

You can do it with a relay, similarly.
Only on the trigger circuit.

 

[silverstone]

(Relay contact + push button) in parallel on the coil of the contactor, alright. Kind of the reversed logic that I though (in this case it needs a "kick start" through the push button to start it [again] )

 

[efficientPV]

I have breakers that if 24V is applied to two isolated leads, the breaker will trip and require manual reset. So those are made. I think mine are CH. They are 800 miles away right now and can't give further detail.

 

[webbbn]

I'm not sure, but I think what you're looking for is called a bistable relay.

 

[silverstone]

I have breakers that if 24V is applied to two isolated leads, the breaker will trip and require manual reset. So those are made. I think mine are CH. They are 800 miles away right now and can't give further detail.

Yes, that's the shunt trip unit for the breaker I mentioned in my original post. I basically just wanted the "shunt trip" without the associated circuit.

 

[silverstone]

I'm not sure, but I think what you're looking for is called a bistable relay.

To some extent yes, BUT:
- If you by mistake (re)apply a pulse to a bistable relay, it will change back to "ON" (CLOSED) state
- Many times the SET and RESET coils are ambivalent, i.e. you might actually RESET the relay by re-applying a pulse to the SET coil
- Dual coils bistable relays are more expensive and rarer, but the same applies to single coils bistable relays: if you re-apply a pulse (by mistake), it will switch back-on
- I have been looking for some "bipolar" coil bistable relay, as I originally thought that if you apply say +24VDC to switch ON a bistable relay, then you needed to apply -24VDC to switch OFF. That would have been easy to interlock, allowing only polarity reversal with a manual pushbutton. But apparently, from what I could gather, it's always +24VDC that is applied to the same coil, regardless if it's to SET or RESET.

I guess what I would really like is some sort of SR flip flop (as in logic circuits).

Just quickly googled it, it seems there are some ideas, but also require several components (AT LEAST 2 relays with 1-2 sets of ChangeOver contacts each) ....

 

[Hedges]

Yes, that's the shunt trip unit for the breaker I mentioned in my original post. I basically just wanted the "shunt trip" without the associated circuit.

Those appear to be DIN rail shunt trip units to gang with a breaker.

Midnight sells some shunt trip breakers, including 175A & 250A battery breakers from Carling.

Category Products - MidNite Solar's

MidNite Solar Category Products.

www.midnitesolar.com

Product - MidNite Solar

MidNite Solar Product Page.

www.midnitesolar.com

They're not explicit about it, but "RT" for remote trip, and shows 24V input on bottom.

 

[webbbn]

There are many relays supported by ESPHome, and I'm sure making an SR flip flop with them would just be a few lines of configuration.

This is an example of a Sonoff relay with a single button toggle. It would be trivial to make it an SR flip flop.

Using With Sonoff Basic

Instructions for putting Sonoff basic devices into flash mode and installing ESPHome on them.

esphome.io

 

[Hedges]

What I am looking for is some kind of "shunt trip unit" Relay that, when energized (say 24VDC or 230VAC) "latches" and disconnects power (contacts configuration change from COM-NO to COM-NC).

I would just like a "Relay" that, when energized, trip its associated circuit, REQUIRING a MANUAL RESET of some sorts (preferrably just a lever). Basically without a breaker.

I thought a remote (shunt) trip breaker would do what you want.

But do you want something that only latches off while power is present, and automatically resets when system power is removed?

A 3PDT relay could be wired for that. Two NC contacts power the load. When a momentary signal is applied to the coil, it lifts the contacts and connects the NO contacts. Third pole could then apply power to coil, latching relay in that position. Interrupting power to it would reset it. Couple diodes could be added to isolate the remote trip and the power for holding in tripped state.