• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Are product labels reliable?

Status
Not open for further replies.

goofeedad

New Member
I recently opened the box of a factory assembled device. the label stated:
V 208
Amp 21.2
3 phase 60 Hz
KW 7.6
Max 35 Amps

I was wondering, how much accuracy can I depend on form this label from the manufacturer?

Is the 7.6 KW the kilowatts it uses per minute, so I multiply that by 60 to get the KW hours?

Why state 21.2 amps and max 36 amps? How can you figure the power consumption like this?
 

KMoffett

Well-Known Member
Not knowing what the device is makes detailed answers pretty difficult. But what the heck, I'll take a stab at it. 21.2 Amps is probably the "normally" operating current. 35 Amps is probably the start-up current or current under maximum load. 7.6Kw is the instantaneous power consumption. In one hour it would use 7.6KWH of electricity.

Why the secrecy about what it is?

Ken
 

Number17

New Member
Its not 7.6kw a min. If it was then you would use 456kw in a hour. Thats insane.
Its 7.6kw an hour.

The 21.2A is probably the average and the 36A the peak.
 

Diver300

Well-Known Member
Most Helpful Member
kW is kilowatts. It is a measure of power. hp or horsepower is another measure of power.

Electricity is metered in kWh, a measure of energy. The energy is the power multiplied by the time, so a 1 kW load for 5 hours is 5 kWh.

208 V is the normal phase to phase voltage on a 3 phase system where the phase to neutral voltage is 120 V.

The power in this case is 3 x 120 x 21.2 = 7632 W which almost exactly what the rating plate shows.

I would say that the 35 Amps is just a peak load and can be ignored if you want to know how much energy it will use.

The device will use up to 7.6 kW, so each hour will be 7.6 kWh. However, it might well use less than that, because many devices don't use their full rated power all the time.
 

bountyhunter

Well-Known Member
Watts are defined as an amount of ENERGY (Joules) per unit time, which is the definition of power. A Watt is defined as a Joule/second.

So, a kilowatt-hour is a load that uses a kilowatt of power which is run for an hour.

BTW: since power (Watts) is a unit of energy/time, it follows that if you multiply it by some unit of time, you end up with energy again. hence kW-hours is an energy unit.
 
Last edited:

bountyhunter

Well-Known Member
Why state 21.2 amps and max 36 amps? How can you figure the power consumption like this?
It tells you that the unit needs a 40A (or more) service from the fuse box to run it.

The power usage is 7.6kW so you pay for 7.6kW-hour for each hour you use it.

I was wondering, how much accuracy can I depend on form this label from the manufacturer?
Probably a bit conservative to avoid law suits.
 
Last edited:
Status
Not open for further replies.

Latest threads

EE World Online Articles

Loading
Top