(diy)Do I need a contactor?

[Christopher Parkinson]

Hi all, I'm building a small, home tanning bed. I finally have a staircase timer which works. It's rated at 16amps. I'm using 10 x 160watt lamps. There is an electronic ballast for each lamp. The ballasts are rated at 1 amp AC 230V output current. Do I need a contactor? The timer manufacturer sales guy says I need a contactor. Is that correct? It does not seem right to me. I'm only using 10 amps. Or am I missing something? If I need a contactor could someone give me a link to one on RS that I can use? It must be din rail type.

What should the breaker be rated at?

Supplementary question: I'm making a US version with 110v AC. There is a 110v version of the staircase timer. I forgot to ask what amperage it is. (I've just sent an email now). On the ballast for that one I've got: Max input current 0.60A @ 230v . (Not sure if the 230v is a mistake - it's a prototype so maybe is a mistake). Lamp Power . 1.96 - 160w. Lamp current 0.80 - 0.90A. What amperage breaker do I need? I think I need a contactor for this one. What amperage contactor do I need? Single pole or dual pole?

 

[westward10]

16A is probably the rating for a resistive load. Your loading is inductive and the rating of your timer will be considerably less for this type of load so I can understand the contactor suggestion.

 

[Pete999]

Hi all, I'm building a small, home tanning bed. I finally have a staircase timer which works. It's rated at 16amps. I'm using 10 x 160watt lamps. There is an electronic ballast for each lamp. The ballasts are rated at 1 amp AC 230V output current. Do I need a contactor? The timer manufacturer sales guy says I need a contactor. Is that correct? It does not seem right to me. I'm only using 10 amps. Or am I missing something? If I need a contactor could someone give me a link to one on RS that I can use? It must be din rail type.

What should the breaker be rated at?

Supplementary question: I'm making a US version with 110v AC. There is a 110v version of the staircase timer. I forgot to ask what amperage it is. (I've just sent an email now). On the ballast for that one I've got: Max input current 0.60A @ 230v . (Not sure if the 230v is a mistake - it's a prototype so maybe is a mistake). Lamp Power . 1.96 - 160w. Lamp current 0.80 - 0.90A. What amperage breaker do I need? I think I need a contactor for this one. What amperage contactor do I need? Single pole or dual pole?

A bit involved for a DIY project CP,

 

[Christopher Parkinson]

is this what I need?

RS Electrical Supplies

RS Electrical Supplies

www.rselectricalsupplies.co.uk

 

[Lucien Nunes]

To determine whether a device will switch a load, e.g. whether your timer will switch the ballasts or whether a contactor is needed, you need to consider a range of compatibility factors. Continuous current rating, peak inrush current, inrush duration, design life in switching cycles, etc. For example, ballasts with an input current of 10A might seem well within the rating of a 16A relay contact, but if they have no internal inrush limiting, a general-purpose relay inside the timer, with AgNi contacts and AC-21 utilisation category, might fall short of design life or even weld closed after just a few thousand cycles. You might mitigate this with NTCs, or add a relay with AgSnO2 contacts or an AC-7 rating, or whatever engineering solution fits your product.

Tip: Contact failure is a common cause of nuisance product breakdowns, often due to 'value engineering' but also sometimes to design errors. Use careful engineering practice, not just asking an internet forum to pick a component off a website, when selecting a switch contact for anything more than trivial duty. I design high-reliability equipment and I choose from amongst many ranges, contact materials, manufacturers etc. to get the performance I need. Sometimes components have to be reverse-engineered to validate the ratings. How many of those timers have you torn down and examined after being put through an accelerated life test with a simulated load? This is what people are hinting at by saying that design of a commercial electrical product, even an apparently simple one, is a long way removed from DIY construction.

 

[Megawatt]

Hi all, I'm building a small, home tanning bed. I finally have a staircase timer which works. It's rated at 16amps. I'm using 10 x 160watt lamps. There is an electronic ballast for each lamp. The ballasts are rated at 1 amp AC 230V output current. Do I need a contactor? The timer manufacturer sales guy says I need a contactor. Is that correct? It does not seem right to me. I'm only using 10 amps. Or am I missing something? If I need a contactor could someone give me a link to one on RS that I can use? It must be din rail type.

What should the breaker be rated at?

Supplementary question: I'm making a US version with 110v AC. There is a 110v version of the staircase timer. I forgot to ask what amperage it is. (I've just sent an email now). On the ballast for that one I've got: Max input current 0.60A @ 230v . (Not sure if the 230v is a mistake - it's a prototype so maybe is a mistake). Lamp Power . 1.96 - 160w. Lamp current 0.80 - 0.90A. What amperage breaker do I need? I think I need a contactor for this one. What amperage contactor do I need? Single pole or dual pole?

Chris the higher the voltage the lower the amperage the lower the voltage the higher the amperage. Good luck

 

[ElectroChem]

is this what I need?

RS Electrical Supplies

RS Electrical Supplies

www.rselectricalsupplies.co.uk

That is the kind of item I would consider when looking for a small contactor for lighting loads.
However, I would never purchase a CHNT anything.

 

[Christopher Parkinson]

Hi Lucien,

I sent you a private message ("Conversation").

 

[Christopher Parkinson]

Hi, I have attached the spec sheet for the lamps I'm using. Can someone please tell me what amperage rating breaker and what amperage rating contactor I need for 230v AC. MCB for the breaker. Correct?
Also, what amperage rating breaker and what amperage rating contactor I need for 110v AC

 

[Lucien Nunes]

The data sheet does not state the ballast input current. The input power is given as 160W so the minimum current is 160/230 = 0.7A, but if the power factor is below unity (depending on whether the ballast has effective PFC) the current will be higher by an unknown amount. In any case the relay / contactor rating may be decided by the inrush rather than the continuous load. For bench-test purposes you might assume 1A per ballast at 230V and 2A at 120V.

Why do you need an MCB? Should it be a CBE or a fuse or multiple fuses? What is its function? Under what conditions would you want it to operate? Is the requirement different for the 120V (not 110V!) USA version? The spec sheet gives the weird +/-0.2% tolerance on the supply voltage which appears to be an error or a test condition, not a rated operating voltage, so again we can't calculate the highest possible current if the supply voltage is low. It's a constant power load, so current increases in inverse proportion to voltage.

You do need to look closely at the load for the USA version, as it is nudging the 15A boundary. Is it intended to connect with a NEMA 5-15? If so, if the pf is good you're just in for running load with 5% below nominal as per NEC, (10 x 160 / 114 = 14A) but if the ballast will operate at say 100V it will go over the 15A. An MCB won't stop that happening and you would have to go up to a 5-20 which is less convenient for domestic users.

 

[Christopher Parkinson]

"The data sheet does not state the ballast input current. The input power is given as 160W so the minimum current is 160/230 = 0.7A, but if the power factor is below unity (depending on whether the ballast has effective PFC) "

What is PFC? What is below unity? Is the jargon for when the actual voltage supply is less than the nominal voltage? (What if it's more?) Would that blow the fuse or trip a breaker?

"the current will be higher by an unknown amount. In any case the relay / contactor rating may be decided by the inrush rather than the continuous load."

Yes. I think I understand what you mean by inrush. That is the surge when it powers up right? So fuse or breaker has to be able to handle the surge without tripping out. Right?

"For bench-test purposes you might assume 1A per ballast at 230V and 2A at 120V.

Why do you need an MCB? Should it be a CBE or a fuse or multiple fuses? What is its function? Under what conditions would you want it to operate?"

What conditions should make it operate? A short or overload right? What other conditions could there be. Could I use one of these fuses?

Fuses | RS Components - https://uk.rs-online.com/web/c/fuses-sockets-circuit-breakers/fuses/?redirect-relevancy-data=636F3D3126696E3D4931384E53656172636847656E65726963266C753D656E266D6D3D6D61746368616C6C7061727469616C26706D3D5E5B5C707B4C7D5C707B4E647D2D2C2F255C2E5D2B2426706F3D31333326736E3D592673723D52656469726563742673743D4B4559574F52445F53494E474C455F414C5048415F4E554D455249432673633D592677633D4E4F4E45267573743D6675736573267374613D667573657326&r=f&searchHistory=%7B%22enabled%22%3Atrue%7D

(I prefer to use a fuse rather than MCB if possible because it keeps my design cleaner and its also lighter - the latter an important consideration) If so, which one?

"Is the requirement different for the 120V (not 110V!) USA version? "

I'm aware that US current is suppose to be 120V but I keep being quoted 110V. I'm told that a little variation in voltage does not matter. For example, UK voltage is supposed to be 230 I believe but Australian voltage is 240v. I was told that the bed would still function ok with Australian voltage.

"The spec sheet gives the weird +/-0.2% tolerance on the supply voltage which appears to be an error or a test condition, not a rated operating voltage, so again we can't calculate the highest possible current if the supply voltage is low. It's a constant power load, so current increases in inverse proportion to voltage. You do need to look closely at the load for the USA version, as it is nudging the 15A boundary. Is it intended to connect with a NEMA 5-15?"

What is a NEMA 5-15? "If so, if the pf..."

What is pf?

"... is good you're just in for running load with 5% below nominal as per NEC,..."

What is NEC? A formula? What is the formula?

".... (10 x 160 / 114 = 14A) but if the ballast will operate at say 100V it will go over the 15A...."

This is assuming that the household has less than nominal voltage right? I think I saw somewhere (aeons ago when I first started this bl oody project) something about a "buck boost" needed for UV tanning equipment in the states when the voltage is lower than it's supposed to be).

"An MCB won't stop that happening and you would have to go up to a 5-20 which is less convenient for domestic users."

What is a 5-20?

 

[DPG]

I would be tempted to use someone with the necessary technical expertise to get this project up and running to be honest. Less risk than designing by web search, and you will end up with a good solution in less time.

 

[Megawatt]

"The data sheet does not state the ballast input current. The input power is given as 160W so the minimum current is 160/230 = 0.7A, but if the power factor is below unity (depending on whether the ballast has effective PFC) "

What is PFC? What is below unity? Is the jargon for when the actual voltage supply is less than the nominal voltage? (What if it's more?) Would that blow the fuse or trip a breaker?

"the current will be higher by an unknown amount. In any case the relay / contactor rating may be decided by the inrush rather than the continuous load."

Yes. I think I understand what you mean by inrush. That is the surge when it powers up right? So fuse or breaker has to be able to handle the surge without tripping out. Right?

"For bench-test purposes you might assume 1A per ballast at 230V and 2A at 120V.

Why do you need an MCB? Should it be a CBE or a fuse or multiple fuses? What is its function? Under what conditions would you want it to operate?"

What conditions should make it operate? A short or overload right? What other conditions could there be. Could I use one of these fuses?

Fuses | RS Components - https://uk.rs-online.com/web/c/fuses-sockets-circuit-breakers/fuses/?redirect-relevancy-data=636F3D3126696E3D4931384E53656172636847656E65726963266C753D656E266D6D3D6D61746368616C6C7061727469616C26706D3D5E5B5C707B4C7D5C707B4E647D2D2C2F255C2E5D2B2426706F3D31333326736E3D592673723D52656469726563742673743D4B4559574F52445F53494E474C455F414C5048415F4E554D455249432673633D592677633D4E4F4E45267573743D6675736573267374613D667573657326&r=f&searchHistory=%7B%22enabled%22%3Atrue%7D

(I prefer to use a fuse rather than MCB if possible because it keeps my design cleaner and its also lighter - the latter an important consideration) If so, which one?

"Is the requirement different for the 120V (not 110V!) USA version? "

I'm aware that US current is suppose to be 120V but I keep being quoted 110V. I'm told that a little variation in voltage does not matter. For example, UK voltage is supposed to be 230 I believe but Australian voltage is 240v. I was told that the bed would still function ok with Australian voltage.

"The spec sheet gives the weird +/-0.2% tolerance on the supply voltage which appears to be an error or a test condition, not a rated operating voltage, so again we can't calculate the highest possible current if the supply voltage is low. It's a constant power load, so current increases in inverse proportion to voltage. You do need to look closely at the load for the USA version, as it is nudging the 15A boundary. Is it intended to connect with a NEMA 5-15?"

What is a NEMA 5-15? "If so, if the pf..."

What is pf?

"... is good you're just in for running load with 5% below nominal as per NEC,..."

What is NEC? A formula? What is the formula?

".... (10 x 160 / 114 = 14A) but if the ballast will operate at say 100V it will go over the 15A...."

This is assuming that the household has less than nominal voltage right? I think I saw somewhere (aeons ago when I first started this bl oody project) something about a "buck boost" needed for UV tanning equipment in the states when the voltage is lower than it's supposed to be).

"An MCB won't stop that happening and you would have to go up to a 5-20 which is less convenient for domestic users."

What is a 5-20?

Chris welcome to the forum and I will answer a couple of your questions. First off in the USA the voltage is 240/120, the NEC is the National Electrical Code which is a book that the USA has to follow for electrical installs. It’s the law and we could possibly go to jail if we wire up something and someone gets hurt or cause a fire. As far as buck and boost, that means wiring transformers together, I don’t know who you was talking to but are you sure they didn’t say 4-20ma ? That’s all I can answer and good luck.

 

[davesparks]

What is PFC? What is below unity? Is the jargon for when the actual voltage supply is less than the nominal voltage? (What if it's more?) Would that blow the fuse or trip a breaker?

What conditions should make it operate? A short or overload right? What other conditions could there be.

I'm aware that US current is suppose to be 120V but I keep being quoted 110V.

What is a NEMA 5-15?

What is pf?

What is NEC? A formula? What is the formula?

What is a 5-20?

PFC is power factor corre tion
PF is power factor
Unity power factor means a power factor of 1
The conditions for the operation of the protection you need to know are things like what level of short circuit current it needs to break, what current it needs to operate at, what an overload condition actually is for you appliance, what type of response you need from the protection slow or fast?

120V is the nominal US voltage, not current

The NEC is the American equivalent of the wiring regulations.

5-15 and 5-20 are two of the many different types of plug and socket used in the US.

 

[Pete999]

PFC is power factor corre tion
PF is power factor
Unity power factor means a power factor of 1
The conditions for the operation of the protection you need to know are things like what level of short circuit current it needs to break, what current it needs to operate at, what an overload condition actually is for you appliance, what type of response you need from the protection slow or fast?

120V is the nominal US voltage, not current

The NEC is the American equivalent of the wiring regulations.

5-15 and 5-20 are two of the many different types of plug and socket used in the US.

You sure about PFC Dave? Thought it stood for Prospective Fault Current.
[automerge]1581096206[/automerge]

You sure about PFC Dave? Thought it stood for Prospective Fault Current.

 

[davesparks]

You sure about PFC Dave? Thought it stood for Prospective Fault Current.
[automerge]1581096206[/automerge]

PFC can be either prospe tove fault current or power factor question.
In this context Lucien mentioned a ballast having PFC built in, so logically must be describing power factor correction.

 

[Pete999]

PFC can be either prospe tove fault current or power factor question.
In this context Lucien mentioned a ballast having PFC built in, so logically must be describing power factor correction.

Maybe Lucien could offer a definitive answer, Lucien?
[automerge]1581096975[/automerge]

PFC can be either prospe tove fault current or power factor question.
In this context Lucien mentioned a ballast having PFC built in, so logically must be describing power factor correction.

I guess this maybe one of the trades myriad of mistakes when using capitals as a description tests and descriptions

 

[davesparks]

Maybe Lucien could offer a definitive answer, Lucien?
[automerge]1581096975[/automerge]

I guess this maybe one of the trades myriad of mistakes when using capitals as a description tests and descriptions

Well a ballast can't have a prospective fault current built in, that is a property of an electricity supply not a physical object you can build in to an item.
A ballast can however have power factor correction built in as this is done by adding components to the ballast.

 

[westward10]

In electrical engineering terms PFC primarily stands for Power Factor Correction. BS7671 does not use the acronym PFC nor is it listed under their abbreviations, prospective fault current is quoted in full and not by an abbreviation I suspect this is the reason why, as the acronym PFC is already utilised.

 

[Christopher Parkinson]

"I would be tempted to use someone with the necessary technical expertise to get this project up and running to be honest. Less risk than designing by web search, and you will end up with a good solution in less time."

>>I've tried 2 so called experts so far. The first one could not tell me why none of the 6 staircase timers I bought would work. It turns out that they needed a momentary push button timer to work. He also told me to use multi core wires on the basis that they were less likely to break. But as the electrician who I called out to get the timer working said: "You will have more chance of connecting things up right with single core. There are 11 connections for each lamp. You only need one bad connection for the lamp not to work"

I thought I had found someone else who was well qualified. (Electrical engineering degree). But he told me to buy a timer which was rated at 3,000 watts and that it would cope with powering the ballasts without having to use a contactor. But when I got the timer it says it's rated at 2,300 watt. Also, he gave me instructions for wiring it up which are not complete. (Where do the wires for the contactor switch go?). He also told me that I did not need a breaker because the fuse in the plug will suffice. But as far as I'm aware it's only UK plugs that have fuses. I intend to sell this thing worldwide.

So how do I find someone with the necessary expertise and how do I know they are a) competent and b) really want to help me. c) affordable

"...First off in the USA the voltage is 240/120,..."

Yes. I'd spotted that. The 240 is mainly for commercial though isn't it? A plug socket in a domestic setting will be 120v. Correct?

You do need to look closely at the load for the USA version, as it is nudging the 15A boundary. Is it intended to connect with a NEMA 5-15? If so, if the pf is good you're just in for running load with 5% below nominal as per NEC, (10 x 160 / 114 = 14A) but if the ballast will operate at say 100V it will go over the 15A. An MCB won't stop that happening and you would have to go up to a 5-20 which is less convenient for domestic users.
Source URL: (diy)Do I need a contactor? - https://www.electriciansforums.net/threads/diy-do-i-need-a-contactor.182902/