# Supply current for power supply and switch

Thread Starter

#### r12345

Joined Jun 22, 2021
7
I have a power supply rated for 85-132 V AC and input current 1.4A.

I bought a plug for it, that is rated 125VAC and 10A.

The power supply will supply 24V to an actuator that is rated for 24VDC and full load 5 A

I also have a switch that is rated for 125V/250V and 15A
DC is 125V and 0.6A
250V and 0.3A

I was thinking I could use the plug for the power supply but I'm not sure if the rating is ok for it. Will the power supply only draw 1.4A and the plug won't oversupply the power supply?

Also is 24V DC supplied from the power supply okay for the switch as well? I need the switch to be instant, and I read that switches are better for AC than DC so I might just supply it with AC, but I need the switch connected to the actuator with a relay

Thank you

#### SamR

Joined Mar 19, 2019
3,845
Welcome to AAC!

Are you plugging this into a residential household circuit? At what voltage? Most residential circuits here (US) on 120VAC are rated @ 15A-20A. Anything plugged into the should be rated for 15A UNLESS it is fused for less. The idea is to break the short-circuited device safely at the rated ampacity of the breaker or fuse in distribution panel without damaging the plugged in device. There is an exception in the Electrical code for residential 20A circuits. IF there is a single receptacle for the circuit it must be rated 20A but IF there are multiple receptacles on the branch then they may be 15A rated. Same would apply to devices plugged into the branch and their plug rating unless further fused by the appliance plugged into the branch. If further fused by the appliance, then that fuse rating applies.

#### LowQCab

Joined Nov 6, 2012
1,622
If your Power-Supply is rated for 1.4-Amps Max,
that equals = ~120-V X 1.4-A = 168-Watts maximum Input-Power.

Your Actuator needs ~24-V, and draws 5-Amps,
24V X 5A = 120-Watts.

That means that your Power-Supply will have to have a efficiency of at least 70%,
that's right on the ragged-edge of realistic plausibility.
Your Power-Supply may not like dealing with this much Load.

What are the Output-Ratings of the Power-Supply ?
What type of Power-Supply is it ?
Is this a cheap Chinese Switching-Supply with adjustable Output-Voltage ?

A Power-Supply with the capability of providing 200% of the Power that you need
would be more appropriate, and insure that you don't over-load it, and burn it up,
or, you may just get poor performance from your Actuator.

Why do you need a Relay, if you are already using a Manual-Switch ?
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Thread Starter

#### r12345

Joined Jun 22, 2021
7
Welcome to AAC!

Are you plugging this into a residential household circuit? At what voltage? Most residential circuits here (US) on 120VAC are rated @ 15A-20A. Anything plugged into the should be rated for 15A UNLESS it is fused for less. The idea is to break the short-circuited device safely at the rated ampacity of the breaker or fuse in distribution panel without damaging the plugged in device. There is an exception in the Electrical code for residential 20A circuits. IF there is a single receptacle for the circuit it must be rated 20A but IF there are multiple receptacles on the branch then they may be 15A rated. Same would apply to devices plugged into the branch and their plug rating unless further fused by the appliance plugged into the branch. If further fused by the appliance, then that fuse rating applies.
Hello, thank you for replying! I see, I don't think it's 10 A, I know it's more than that. There are multiple things plugged into the circuit supplying the 125VAC, so I'll get a 15 A plug. What do you mean by fused by the appliance?

Thread Starter

#### r12345

Joined Jun 22, 2021
7
If your Power-Supply is rated for 1.4-Amps Max,
that equals = ~120-V X 1.4-A = 168-Watts maximum Input-Power.

Your Actuator needs ~24-V, and draws 5-Amps,
24V X 5A = 120-Watts.

That means that your Power-Supply will have to have a efficiency of at least 70%,
that's right on the ragged-edge of realistic plausibility.
Your Power-Supply may not like dealing with this much Load.

What are the Output-Ratings of the Power-Supply ?
What type of Power-Supply is it ?
Is this a cheap Chinese Switching-Supply with adjustable Output-Voltage ?

A Power-Supply with the capability of providing 200% of the Power that you need
would be more appropriate, and insure that you don't over-load it, and burn it up,
or, you may just get poor performance from your Actuator.

Why do you need a Relay, if you are already using a Manual-Switch ?
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It's a 6EP1332-4BA00 Siemens power supply with a 24VDC output.

The output current of the power supply will be at the max 3A.

These are the current for the loads, and the load I'll have will at the most be 5 pounds. I guessed that the power supply would be able to handle that.

I wanted to control the actuator with both a PLC and the switch. I would use the PLC to make the actuator move until the limit switch hit something. I was thinking of using a relay for that.
I wanted to power the switch through the PLC but now I'm thinking maybe it will have to be powered by AC.

#### LowQCab

Joined Nov 6, 2012
1,622
OK,
assuming that your Actuator will always be very lightly Loaded,
the Power-Supply will probably be adequate.

Now you have added-in a PLC-Controller ..........
Plus an over-ride Switch.
Plus Limit Switches.

What type of Output does the PLC-Controller have ?
Is it a set of Relay Contacts ?
Is it a DC or AC Voltage ?

Does your Actuator need to be Reversible ?

What type and arrangement of Limit-Switches are you using ?

What does this Actuator Actuate ?
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Thread Starter

#### r12345

Joined Jun 22, 2021
7
OK,
assuming that your Actuator will always be very lightly Loaded,
the Power-Supply will probably be adequate.

Now you have added-in a PLC-Controller ..........
Plus an over-ride Switch.
Plus Limit Switches.

What type of Output does the PLC-Controller have ?
Is it a set of Relay Contacts ?
Is it a DC or AC Voltage ?

Does your Actuator need to be Reversible ?

What type and arrangement of Limit-Switches are you using ?

What does this Actuator Actuate ?
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I don't have an override switch, just a limit switch. The output of the PLC is 24V DC. Just inputs and outputs.

The actuator does need to be reversible.

I'm using these
https://www.amazon.com/12Pack-Ardui...ds=MUZHI+SPDT+24V&qid=1624376090&sr=8-14&th=1

The actuator is a linear actuator that will go up when the PLC says to and it'll continue rising until it hits something. I'm wanting to use the limit switch to stop the actuator.
When the object it hits is gone, I want the actuator to go back to its original location

#### SamR

Joined Mar 19, 2019
3,845
fused by the appliance?
Some pieces of electrical equipment (appliance) have a fuse located at their electrical feed point to protect circuits that are designed for less than the typical 15-20A receptacle feed. Usually found on the rear chassis next to the cordset.

#### LowQCab

Joined Nov 6, 2012
1,622
Here's how ya do it .........
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Thread Starter

#### r12345

Joined Jun 22, 2021
7
Some pieces of electrical equipment (appliance) have a fuse located at their electrical feed point to protect circuits that are designed for less than the typical 15-20A receptacle feed. Usually found on the rear chassis next to the cordset.
We don't have a fuse or breaker yet but in the future we'll probably get one since it's a good idea in general

Thread Starter

#### r12345

Joined Jun 22, 2021
7
Here's how ya do it .........
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View attachment 242023
Oh wow thank you so much, I'll look into this
I guess it's not possible to accomplish it with just PLC outputs, one limit switch, and one relay

#### LowQCab

Joined Nov 6, 2012
1,622
Well, just to complicate matters,
you could eliminate the Limit-Switches and replace them with a single
Hall-Effect-Current-Sensor on one of the Actuator-Motor-Leads.
This would have the bonus of reversing the Motor if it got jammed / blocked somehow,
and it would make a much cleaner installation.
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#### SamR

Joined Mar 19, 2019
3,845
Just about anything can be done in a PLC. Especially relay and switch logic.

Thread Starter

#### r12345

Joined Jun 22, 2021
7
Well, just to complicate matters,
you could eliminate the Limit-Switches and replace them with a single
Hall-Effect-Current-Sensor on one of the Actuator-Motor-Leads.
This would have the bonus of reversing the Motor if it got jammed / blocked somehow,
and it would make a much cleaner installation.
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Would the current increase or decrease based on if the actuator hits something?

#### LowQCab

Joined Nov 6, 2012
1,622
There will be a very short spike in Current the instant that the Motor Starts,
Current will then run at a nominal , somewhat low, value,
in between the Starting and Stopping points.
This will depend on, and vary with,
how much weight or Friction the Motor is having to overcome in doing it's job.

But if something tries to stop the Motor, or even slow it down substantially,
the Current will instantly rise towards what is called "Locked-Rotor-Amps",
which will probably be 3 to 6 times as high as "normal-running-Amps".

These changes in Current are very easy and obvious to detect with a Current-Sensor.
How the Current Sensor can be interfaced with you PLC-Controller will depend
upon what types of Inputs it requires.

If you PLC will only accept "Hi-or-Low" Inputs, some additional Circuitry will
have to be added to establish a Current-Level "Switching-Point" for the Input,
because the Output of the Current-Sensor is a varying Voltage that
represents the amount, and Direction of, Current flow.

On the other hand, if your PLC will accept a varying Voltage-Input,
then the Current-Sensor could be directly connected to it.
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#### LowQCab

Joined Nov 6, 2012
1,622
A Current-Controlled Actuator does have a draw-back when compared to using a Limit-Switch.

The Current-Controlled setup actually has to
hit some sort of "Stop", or hit the "End of Travel" of the Actuator,
before the Current will increase enough to create a signal to Stop or Reverse.

Now, the interesting part ........
You can use both types of systems for control at the same time.

You can use a Limit-Switch to Stop, or Reverse motion,
without actually having to hit a mechanical stop or bumper,
while at the same time, the Current-Sensor will prevent damage to anything that
might occur if something jams, or blocks, or tries to stop the Actuator from moving.

You might want this Actuator to very firmly close a Door of some sort,
in this case, the Current-Sensor is the way to go, because it won't stop until
a certain number of pounds of force are exerted by the Actuator.
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