[SOLVED] Relay type

[Basketcat]

Is there a specific name or type that defines the difference between these relays? Both seem to be called power relays, but the Panasonic one appears to have a movable contact part (I hear a clicking noise when shaking it). Additionally, the movable contact part sometimes gets stuck at the NO pin and need to be knock , shake to get back to NC , while the other relay never causes any issues.
Thank you in advance if someone could provide me with information so I can avoid this type of relay when ordering parts.

 

[barry]

They are both electromechanical relays, and, thus, both have moving parts. There’s no part number on the imron part, so can’t compare them

 

[stenzer]

Hi,

as mentioned by @barry they have both moving parts. The one which got "stuck" (OMRON) might be a latching/bistable relay, please provide the part-number.

BR

 

[FvM]

Neither relay type is bistable. Getting stuck (contact welding) can happen if a mechanical weak relay switches capacitive load. The Omron relay has bigger contacts and most like higher drive force than Panasonic, thus less prone to welding. Notice that Panasonic is specified for resistive load only.

--- Updated Jun 19, 2024 ---

Would be helpful to know the exact Omron type specification, I guess it's G2R series.

 

[Basketcat]

Neither relay type is bistable. Getting stuck (contact welding) can happen if a mechanical weak relay switches capacitive load. The Omron relay has bigger contacts and most like higher drive force than Panasonic, thus less prone to welding. Notice that Panasonic is specified for resistive load only.

--- Updated Jun 19, 2024 ---

Would be helpful to know the exact Omron type specification, I guess it's G2R series.

Omron one is G2r-24vdc

--- Updated Jun 19, 2024 ---

I used to crack open the Panasonic one, and the part that was making the clicking noise would fall off like it wasn't connected to anything.
It's a bit hard to avoid ordering a relay without knowing the specific name of the type. Because of the solid shell cover, I can't see the mechanism inside like in Omlon.

A similar relay to Omlon would be the Idec RU2V-NF-D24. This one also never causes any problems (no clicking noise).

--- Updated Jun 19, 2024 ---

I checked back at the Panasonic datasheet. It doesn't mention inductive or capacitive loads, so that might be the reason this Panasonic's mechanism is only designed for resistive loads. (my load is magnetic lock ) Thank you sir.

 

[dick_freebird]

Contact welding is affected by the arc power on
opening, and by the contact material system.
Soft contact platings s like Ag, Au have better
ohmic resistance but can weld at lower arc energy.
A non-fancy relay may not even tell you about
contact material but will tell you a peak current
and suitability for inductive loads.

A contact snubber can be a big help with reactive
loads.

Might step back a little and think about what you
are trying to do. Might just need a little band-aid
(snubber) or might want a whole different switch
(power FET? power BJT?) if electromechanical
attributes (noise, coil current, contact welding) are
problematic..

 

[Basketcat]

Contact welding is affected by the arc power on
opening, and by the contact material system.
Soft contact platings s like Ag, Au have better
ohmic resistance but can weld at lower arc energy.
A non-fancy relay may not even tell you about
contact material but will tell you a peak current
and suitability for inductive loads.

A contact snubber can be a big help with reactive
loads.

Might step back a little and think about what you
are trying to do. Might just need a little band-aid
(snubber) or might want a whole different switch
(power FET? power BJT?) if electromechanical
attributes (noise, coil current, contact welding) are
problematic..

thank you for your suggestion ill try contact snubber for my circuit.
and sorry i didnt explain clearly

I use ML to lock and unlock the door. This is my diagram: Diode D2 is for protection of the coil,
D1 (Reverse Voltage Max 400V). The ML consumes a load of 0.7 A.
I added C1 later because the ML lock noise was really loud, so I added it to create a discharge delay.

The things I noticed before and after adding C1 are:
Before adding C1 ---> while using the relay, the problem of the coil getting stuck still happened,
but very rarely.(fix by knock at relay at contract coil go back to NC - I check again by degital meter)

After adding C1---> and make discharge delay around 0.3s after press on-off around 4-5 times contract coil is stuck.
so i test for 10 times+ and it happens repeatedly and clearly

So, I started to check the Panasonic relay (even cracking it open) and noticed that the mechanism was as I suspected.
I then switched to Omron and Idec relays, which looked more secure.
The problem I found with the Panasonic relay never happened with these two relays,
even after turning them on and off repeatly more than 100+ times.

And I didn't bother to look back at the datasheet. I didn't know this type of load would cause the coil to get stuck;
I was only worried about the coil melting due to overcurrent or voltage.

 

[D.A.(Tony)Stewart]

Is there a specific name or type that defines the difference between these relays? Both seem to be called power relays, but the Panasonic one appears to have a movable contact part (I hear a clicking noise when shaking it). Additionally, the movable contact part sometimes gets stuck at the NO pin and need to be knock , shake to get back to NC , while the other relay never causes any issues.
Thank you in advance if someone could provide me with information so I can avoid this type of relay when ordering parts.

View attachment 191687 View attachment 191688

Contact stiction is a symptom of exceeding the life expectancy most likely under-rated from ignoring the derating requirements from the most reliable designer of relays, namely, (Hitachi )+ omRon.

Albeit this is ancient technology, the contact ratings must be reduced by the power factor of the load with appropriate snubbers to suppress extended stored energy arcs burning the contacts without significantly slowing down the open response time from a too-low impedance snubber.

FAQ02804 for General Purpose Relays | OMRON Industrial Automation

Choosing from among CR elements, diodes, varistors, and other kinds of surge suppressor elements, which is the most effective for protecting contacts?

www.ia.omron.com

OMRON - MY type

--- Updated Thursday at 4:50 PM ---

The best relays include expensive vacuum-sealed not practical here. You cannot judge the reliability of a relay by its cover, but rather from MTBF specs which Omron used to publish before they began promoting their FET Relays. The clear plastic cases are good for inspection and cooling with large gaps using silver alloy bifurcated contacts, yet are exposed to humidity oxidation effects from inactivity.

An OMRON relay will switch mechanically > 1e6 cycles and all relays may fail in 1e3 cycles if you choose a relay size to match a motor's rated current value since start surges can be 500% and back EMD with a dry contact is guaranteed to create enough V=LdI/dt to create an arc on the contacts which may not be sufficient to extinguish at zero-voltage crossing due to low p.f. until the motor has slowed down enough. OMRON at one time showed the expected MTBF curves for all load types. Now you use a rating 2.5 x the motor current for pf = 0.4. Some relay types can not be used for DC motors for obvious reasons ( no zero crossing to start extinguishing the arc)

--- Updated Thursday at 5:03 PM ---

thank you for your suggestion ill try contact snubber for my circuit.
and sorry i didnt explain clearly

View attachment 191737
I use ML to lock and unlock the door. This is my diagram: Diode D2 is for protection of the coil,
D1 (Reverse Voltage Max 400V). The ML consumes a load of 0.7 A.
I added C1 later because the ML lock noise was really loud, so I added it to create a discharge delay.

This is not a good snubber design.

You have massively increased the turn-on surge current with the Cap. I= 24V/ ESR [A]

The general solutions are
Methods available to prevent contact arcing

1. Diode.
2. Resistor-Capacitor [Snubber]
3. Resistor-Capacitor-Diode [R-C-D]
4. Back to Back Zener Diode.
5. Metal Oxide Varistor [MOV]

I recommend you use 5 with 3. The R reduces the surge current and Q of the LC resonance.

 

[Basketcat]

Contact stiction is a symptom of exceeding the life expectancy most likely under-rated from ignoring the derating requirements from the most reliable designer of relays, namely, (Hitachi )+ omRon.

Albeit this is ancient technology, the contact ratings must be reduced by the power factor of the load with appropriate snubbers to suppress extended stored energy arcs burning the contacts without significantly slowing down the open response time from a too-low impedance snubber.

FAQ02804 for General Purpose Relays | OMRON Industrial Automation

Choosing from among CR elements, diodes, varistors, and other kinds of surge suppressor elements, which is the most effective for protecting contacts?

www.ia.omron.com

OMRON - MY type
View attachment 191743

--- Updated Thursday at 4:50 PM ---

The best relays include expensive vacuum-sealed not practical here. You cannot judge the reliability of a relay by its cover, but rather from MTBF specs which Omron used to publish before they began promoting their FET Relays. The clear plastic cases are good for inspection and cooling with large gaps using silver alloy bifurcated contacts, yet are exposed to humidity oxidation effects from inactivity.

An OMRON relay will switch mechanically > 1e6 cycles and all relays may fail in 1e3 cycles if you choose a relay size to match a motor's rated current value since start surges can be 500% and back EMD with a dry contact is guaranteed to create enough V=LdI/dt to create an arc on the contacts which may not be sufficient to extinguish at zero-voltage crossing due to low p.f. until the motor has slowed down enough. OMRON at one time showed the expected MTBF curves for all load types. Now you use a rating 2.5 x the motor current for pf = 0.4. Some relay types can not be used for DC motors for obvious reasons ( no zero crossing to start extinguishing the arc)

--- Updated Thursday at 5:03 PM ---

This is not a good snubber design.

You have massively increased the turn-on surge current with the Cap. I= 24V/ ESR [A]

The general solutions are
Methods available to prevent contact arcing

1. Diode.
2. Resistor-Capacitor [Snubber]
3. Resistor-Capacitor-Diode [R-C-D]
4. Back to Back Zener Diode.
5. Metal Oxide Varistor [MOV]

I recommend you use 5 with 3. The R reduces the surge current and Q of the LC resonance.

Thank you, sir. I also noticed that the arc still happened as well. I'll try your method 5 and 3.

 

[Basketcat]

Ark happened

i added RCD snubber MKP cap 275Vac 1uf + diode1n5404+ R1kohm 1w to NO pin

Ark gone from contact coil

Thank you, everyone. I learned a lot of things from this topic."