solid state relays

[gerryr1gerry]

I apologise if this is not the correct forum for my query but here goes anyhow.

I am using a solid state 32V DC 240V AC rated 40 Amp relay to turn off and on a irrigation pump remotely.

The pump is 240V Single p\Phase drawing 18 AMP at start up.

My old relays had the 240V connections both in and out for both active and neutral wires.

The new SS relay however has only two connections on the 240 V side.

I have tried to use the two terminals as a switch (ie Positive wire in and positive wire out) thinking the relay acts as a switch for the active wire only. I have also tried connecting both terminals to the Neutral wire but nothing works.

Can anyone tell me what I am doing wrong.

Any advice ( even insulting ) would be greatly appreciated.

 

[RCinFLA]

Normally 240 vac connect pumps in U.S. use a double pole, single throw relay. There should be no neutral connection for a 240 vac pump. There should be a green grounding wire to case.

The reason for using double pole is to avoid leaving 120 vac on motor winding to ground.

Solid state switches have about 1.6 vdc drop due to two equivalent diode drops associated with triac switch. What is more important is the run current. This causes the steady state heating of the SS switch. The SS switch needs to be heat sunk sufficient to dissipate the heat generated by its voltage drop (1.6 vdc) times the current it is passing.

You can place two SS switches, one on each L1 and L2 lines, tieing the control lines together.

You have a wiring problem and may have already blown out the triac. When you said you switched Neutral line that's a red flag that you may have screwed up the connections, as neutral should not exist running to the 240 vac pump. (neutral is white wire, L1 & L2 should be red, black, and ground wires should be green.).

 

[gerryr1gerry]

Tx for your reply.I should have mentioned I am in Australia. Standard 240V AC current. Brown active. Blue neutral.
Our standard cable has Brown, Blue and Green .I have wired up the pump normally then split the Brown active wire and connected that to Pole 1 on the relay.Pole 2 then carries on to the motor which I would have assumed completed the circuit when the Relay activates.If all else fails I will try your suggestion of 2 SS switches. I guess one SS would go in the active line and other SS in the neutral line.My concern with 2 relays is the switching current which is 24V DC but only 1 mamp.The current on the switching line would then have to trigger 2 SS Relays and 2 24V DC solenoids in the irrigation line.

Would appreciate your comments

Thanks

 

[Reloadron]

The attached is a simple image of a SSR circuit. Generally they don't care which side the load is on. Either A or B should work. This assumes that the Australian power is 240 VAC Line to Neutral as you explained.

You mention that your control voltage is 24 VDC and you also mention 1 mA. Most SSRs that use DC control use a control voltage between 3 ~ 32 volts. Could you provide a link to the part number / model number of the specific SSR you have? When you say 1 mA are you caying that your control voltage is limited to 1 mA? That sounds a little low for most generic SSR relays.

Something you could try if possible is to use maybe a 9 volt battery just to test the SSR and see if it turns the pump on. That would tell you if the problem is the control voltage inability to turn on the SSR.

All of this assumes a known good pump and I assume the pump is on a circuit breaker (GFIC) or fused in accordance with Australia electrical codes.

Just My Take
Ron

 

[Martel]

I do not know the actual power mains characteristins in Australia.

If you have one live 240 VAC line and a 0V neutral, use ONE SS relay on the LIVE wire and keep the 0V neutral intact.

If you have TWO 120 VAC lines that add-up for 240VAC, then use TWO SS relays, one per phase.

NEVER, i say, NEVER cut the ground wire !

 

[RCinFLA]

You only need one SS switch in the brown (hot) wire. Usually SS switches don't care which one of the two terminals is used for load or AC line side.

If SS switch has hot labeled and load labeled it is only because it is preferred to avoid part of the triac gate driver circuitry being on the hot line when 'off' where it may be more subject to lightning surges that would be more inclined to damage triac driver. It will operate either way.

Other thought, are you sure you have D.C. to run SS switch control. Regular coil relays normally use 24 vac or line voltage AC to power relay coil. You can get SS switches that take 24 vac for control line if that is what the control voltage is.

 

[rags]

Dual line switching

Hi guys,

Just reading through this post and thought I would add my thoughts.

Switching just the live (hot) side will work fine from a pump-run point-of-view. BUT, if the mains power supply lines to the installation have been crossed over (incorrectly wired), then you will have mains power connected to the pump and just the neutral switched off.

The pump will not run but mains power will still be present under the electrical covers and you won't know unless check it with a voltmeter. This would very dangerous if someone were to work on the wiring thinking that the power was off.

So, my advice is to switch both line and neutral and you won't have a problem.

Cheers,

Rags

 

[carmusic]

even in america with split phase120-neutral-120 you only put one ssr, the reason is simple, when ssr are at off there some leakage (about 1 to 100ma depending on ssr), so even if the 2 ssr are off there will be some voltage on load, ssr are not for isolating a load, there must be in series with mechanical switches, relay if isolation is needed.

 

[kinarfi]

Here's how I see it.