Hi,

All the specs/instructions that I can find for the Kanalog/Konnect talk about the output specs for DC only.

Kanalog Relay FET switches = 24V, 1amp

Kanalog Opto outputs = 80V, 0.025A

Konnect Opto outputs = 30V, 0.25A

I have some 3 phase contactors that use AC for their input coil (the mill has a 24V AC output on it's transformer that it used to switch the contactor) and I wonder if any of the Kanalog/Konnect outputs are capable of switching a 24V AC signal on/off?

If it is not possible, I guess I will need to add an extra SSR for each output, but that is a handful of relay's that I'd rather avoid if possible.

Regards,

Tim

I can't really speak for the Kanalog, but you can run an AC coil from DC, provided you use a lower voltage. Measure the coil resistance (R) with a DC multimeter (most DMMs will be DC). Get the RMS current specification (I, Amps) for the contactor coil. Then compute the required voltage using V = IR. Since the Kanalog driver will put out 24V, subtract V from that, leaving a lower voltage U. Although it is somewhat wasteful, you can drop the voltage by U using an appropriate series resistor Rs = U/I. Just make sure the resistor power rating is at least UI (Watts).

Hope this helps,

On Sun, Feb 1, 2015 at 10:47 PM, timbosaurus@... [DynoMotion] <DynoMotion@yahoogroups.com> wrote:

Hi,

All the specs/instructions that I can find for the Kanalog/Konnect talk about the output specs for DC only.

Kanalog Relay FET switches = 24V, 1amp
Kanalog Opto outputs = 80V, 0.025A
Konnect Opto outputs = 30V, 0.25A

I have some 3 phase contactors that use AC for their input coil (the mill has a 24V AC output on it's transformer that it used to switch the contactor) and I wonder if any of the Kanalog/Konnect outputs are capable of switching a 24V AC signal on/off?

If it is not possible, I guess I will need to add an extra SSR for each output, but that is a handful of relay's that I'd rather avoid if possible.

Regards,
Tim

Thanks AB, that's a good suggestion that I'll try if the outputs are not capable of switching AC.

looking at the konnect output circuit, i don't think the transistor on the opto output would be compatible with a reverse voltage. so it looks like either switching to dc or an additional relay :(

Hi Tim,

You are correct the transistor output will only pass current one direction. I suppose you could add a small full bridge rectifier.

Why not just use a DC Relay?

Regards

Group: DynoMotion	Message: 11017	From: timbosaurus	Date: 2/3/2015
Subject: Re: switching AC with Konnect or Kanalog

Hi Tom, thanks for confirming.

The 'relay' is actually a 3ph contactor with over-current limiting, so would be fairly expensive to replace.

I'll see how I go finding a suitable DC voltage to drive the AC coil, and if that doesn't work, I'll add a DC-AC relay inline.

Group: DynoMotion	Message: 11018	From: Steve Klemp	Date: 2/3/2015
Subject: Re: switching AC with Konnect or Kanalog

In the past I used a dc ice cube relay to switch the ac coil of a contactor. It worked just fine. Just be sure to add a fly back diode to the relay coil.

------------------------------

On Tue, Feb 3, 2015 10:04 PM CST timbosaurus@... [DynoMotion] wrote:

>Hi Tom, thanks for confirming.
>
> The 'relay' is actually a 3ph contactor with over-current limiting, so would be fairly expensive to replace.
>
>
> I'll see how I go finding a suitable DC voltage to drive the AC coil, and if that doesn't work, I'll add a DC-AC relay inline.

Group: DynoMotion	Message: 10974	From: timbosaurus	Date: 2/1/2015
Subject: switching AC with Konnect or Kanalog

Group: DynoMotion	Message: 10976	From: Hardy Family	Date: 2/2/2015
Subject: Re: switching AC with Konnect or Kanalog

Group: DynoMotion	Message: 10998	From: timbosaurus	Date: 2/2/2015
Subject: Re: switching AC with Konnect or Kanalog

Group: DynoMotion	Message: 11008	From: timbosaurus	Date: 2/2/2015
Subject: Re: switching AC with Konnect or Kanalog

Group: DynoMotion	Message: 11011	From: Tom Kerekes	Date: 2/3/2015
Subject: Re: switching AC with Konnect or Kanalog