Mains transformer for 50Hz and 400Hz use?

[Flyback]

Hi,
Is it likely that for a mains transformer based offline power supply....it's transformer would be perfectly ok for use with 50Hz or 400Hz? I mean, is it usual to see such designs whereby its ok for 50Hz or 400Hz?

 

[ChrisP58]

Audio power transformers for constant voltage speaker systems cover that frequency range.

I doubt that there are any off the shelf ones that match the mains voltage, but it shouldn't be difficult to rewind them for the different voltage.

 

[Diver300]

I think that a 400 Hz transformer would have thinner laminations, or use a ferrite core, so a 50 Hz transformer might have more eddy current heating at 400 Hz.

 

[ronsimpson]

I think a 50hz transformer will be just fine at 400hz.
Do not use a 400hz transformer at 50hz! The primary inductance is too low. The number of turns is too low. The volt seconds rating transformer is too low.

 

[Diver300]

The Volt-seconds rating of a transformer is important, so a using a 400 Hz transformer at 50 Hz has to be with no more than 1/8th of the rated supply voltage.

The primary inductance may be too low, but that depends on what circuit is supplying it. There may be a lot of primary current even without a load on the secondary.

 

[Buk]

A given transformer, at a given current, will have 50x greater total losses (hysterysis, proximity, eddy current and resistive combined) at 400Hz than it does at 50Hz.

Whether this is important depends upon what ratio, power and frequency the transformer was designed for.

eg. This overly conservative, 20:1 (240v/12v) E-core transformer designed for 1A output @12V from a 240VAC input:

has 0.25 mW of total losses when used at 50Hz:

but at 400Hz, it generates 13mW of heat:

Insignificant for this design and use, but a less conservative design it could become significant.

Ie. Your question does not contain enough information to give a definitive answer.

What frequency and power draw was it designed for?
What frequency and power draw do you wish to utilise it for?

 

[crutschow]

is it usual to see such designs whereby its ok for 50Hz or 400Hz?

I doubt there're many devices that operate on both, as 400Hz is usually only used on aircraft to save magnetic material weight, since significantly less is required for transformers and motors.

If you needed this, you would likely have to have a custom transformer designed that has low losses at 400Hz, but a large enough core that will not saturate at 50Hz.

 

[Flyback]

What frequency and power draw was it designed for?
What frequency and power draw do you wish to utilise it for?

Thanks, Its for mainly 50Hz use, and for a linear regulator of power output 69V and 5A.

I doubt there're many devices that operate on both, as 400Hz is usually only used on aircraft to save magnetic material weight, since significantly less is required for transformers and motors.

Thanks, what about yachts say 20 foot to 200 foot?....do they use 50Hz or 400Hz.?....or DC distribution?

 

[Diver300]

Thanks, what about yachts say 20 foot to 200 foot?....do they use 50Hz or 400Hz.?....or DC distribution?

As far as I know, small boats will use 12 V dc or 24 V dc, so that they can run most stuff from the batteries without the engines running.

Where there is a generator that directly powers loads, and the generators are expected to be running most of the time that there isn't shore power, the power will be 50/60Hz, 230/120 V, depending on which country's system the owner wants.

I've never heard of 400 Hz equipment on boats.

 

[Flyback]

the power will be 50/60Hz, 230/120 V, depending o

Thanks i imagine its pseudo sine and no iron transformers anywhere...just rectifiers....the only iron woudl likely be in the genny?

 

[Diver300]

Thanks i imagine its pseudo sine and no iron transformers anywhere...just rectifiers....the only iron woudl likely be in the genny?

Inverters on boats may use high frequency transformers, but I have also seen ones with 50/60 Hz transformers a few years ago.

I would guess that most boat generators are 3000 / 3600 rpm. I suppose that inverter generators will be used sometimes, but compared to the Diesel engine the electrical machine is quite small.

A 50/60 Hz generator that is attached to the engine used for propulsion could benefit from being an inverter type as the speed of the engine will vary. However, on larger boats there are separate generators.

I had a look around a tug once. It was about 50 foot long. It had no gearbox, so the propellor was mounted on the crankshaft, and the engine was started in reverse in order to drive astern. That would have been really inconvenient for driving a generator, and the electricity came from a separate, constant speed engine.

 

[Buk]

Thanks, Its for mainly 50Hz use, and for a linear regulator of power output 69V and 5A.

Changing the turns ratio and coil currents of my (preexisting) model to match that -- 4:1 turns ratio (800/200); with 1.45A in the primary and 5A in the secondary, the total losses calculated are:

50Hz -> 0.3W
400Hz -> 19.3W

This is a 37 x 45 x 11 x 4 x 0.18 lamiinated steel e-core, with 0.25mm primary and 1.0mm secondary wire; which almost certainly doesn't match your actual unit, so don't take the absolute values as having any applicability; but the relative difference does show the dramatic increase in losses with the change from 50Hz to 400Hz.

 

[crutschow]

Why the interest in 400Hz power?

 

[Flyback]

400Hz interest...because for some reason, someone asked if it was ok to put "50-400Hz" on the label for a transformer based PSU....and it said 50-400Hz....i said no , dont do that, because it woudl overheat t 400Hz......but maybe it woudl heat up more but still be ok

 

[ronsimpson]

A given transformer, at a given current, will have 50x greater total losses (hysterysis, proximity, eddy current and resistive combined) at 400Hz than it does at 50Hz.

Why does the resistive losses go up with frequency? (400hz so not skin effect)

Hysteresis loss goes up by 400/50.

 

[Buk]

Why does the resistive losses go up with frequency? (400hz so not skin effect)

The figures quoted are core losses only.

There's more data available from the simulation -- and much more can be derived with some more simulation time and some complex math -- but it is of little relevance, given the core used for this quick example bears no relation to the real one.

50Hz:                                     

Primary coil:

    Total current = 1.45 Amps                         
    Voltage Drop = 19.6083+I*80.2979 Volts                     
    Flux Linkage = 0.255596-I*0.0105389 Webers                 
    Flux/Current = 0.176273-I*0.00726818 Henries                 
    Voltage/Current = 13.523+I*55.3779 Ohms                     
    Real Power = 14.2161 Watts                         
    Reactive Power = 58.216 VAr                         
    Apparent Power = 59.9266 VA                         

Secondary coil:

    Total current = 5 Amps                             
    Voltage Drop = 0.0401706-I*16.0447 Volts                 
    Flux Linkage = -0.0510719+I*0.0026672 Webers                 
    Flux/Current = -0.0102144+I*0.000533439 Henries                 
    Voltage/Current = 0.00803411-I*3.20894 Ohms                 
    Real Power = 0.100426 Watts                         
    Reactive Power = -40.1118 VAr                         
    Apparent Power = 40.1119 VA                         

Hysteresis, laminate eddy and Proximity integral:

    0.298752 Watts                                 


400Hz:

Primary coil:

    Total current = 1.45 Amps
    Voltage Drop = 224.228+I*595.961 Volts
    Flux Linkage = 0.237125-I*0.0827329 Webers
    Flux/Current = 0.163535-I*0.0570572 Henries
    Voltage/Current = 154.64+I*411.007 Ohms
    Real Power = 162.565 Watts
    Reactive Power = 432.071 VAr
    Apparent Power = 461.642 VA

Secondary coil:

    Total current = 5 Amps
    Voltage Drop = -51.5054-I*115.837 Volts
    Flux Linkage = -0.0460899+I*0.0208427 Webers
    Flux/Current = -0.00921798+I*0.00416854 Henries
    Voltage/Current = -10.3011-I*23.1673 Ohms
    Real Power = -128.764 Watts
    Reactive Power = -289.591 VAr
    Apparent Power = 316.928 VA

Hysteresis, laminate eddy and Proximity integral:

    19.3371 Watts

 

[ronsimpson]

What software are you using?

 

[Buk]

What software are you using?

FEMM

 

[AnalogKid]

I've never heard of 400 Hz equipment on boats.

Welcome to the United States Navy. MIL-STD-1399-300B (2008) defines the Type I power system with 60 Hz AC, and Type II and Type III power systems with 400 Hz AC.

Because so many of our projects went into environments where 400 Hz AC *might* be present, we shifted to using high-speed rectifiers on anything MIL.

Commercial boats use 50/60 Hz power so that normal fixtures and devices work as on land. Big yachts usually are built with whatever power standard is in the country of the initial owner.

ak

 

[ronsimpson]

I find it interesting that 400hz transformer are smaller than 50/60hz transformers. I work with 100khz to mhz transformers and the higher frequency the smaller the core needs to be. I just don't see 50x more core loss.