Electronics Forum / Electrical Engineering / October 2005

When I control a BLDC using 3 PWM signals, do my PWM signals have to
be phase shifed by 120 degrees?
I have a hall sensor to decide when to switch the MOSFETS.
Thanks.

Can anybody explain, which is the lower current that a current
tranformer can sense, I want it to use for sensitive earth fault
protection.
If I have a 20:1 CT (window CT for homopolar sensing) which is lower

I'm collecting names of companies/suppliers who offer free posters or
other similar marketing material shipped to the US.  Anything from
charts used for sizing to catalogs that weigh on the side of
educational literature to more recreational posters of space ships,

We are in Canada and starting to look at IEC 6001-4-2
compliance to sell into Europe.  One product failed
its spark discharge test.  We don't have US$2500 to
spend on an ESD gun, so we replicated the problem

Is it acceptable to use a general purpose relay (which does not have a HP
rating on it) to start and run a fractional hp motor (up to 1/2 hp) ?  The
motor will have built in automatic overload protection.  The relay would
have a higher rating than the motor amperage.

An amazing example of how electricity can bridge a large air gap and keep a
connection live even after the breakers go.
http://www.digitalfog.com/gallery/electrical.html

You know those little connectors used on a PC motherboard to connect the
speaker, power switch, hard drive LEDs etc, the ones with a single row of
(usually 2, 3 or 4) pins.  What are they called, are they easily obtained
from suppliers, and how easy are they to attach to a cable ...

I want to be able so select the right motors for the right
applications. Very often people
choose motors on behalf of their experience only, not knowing why and
how. This bothers me. I want to be able to select motors such as Shunt

Does anyone have any concrete numbers as to how much accuracy there is
in trying to measure torque by measuring motor current? I've heard some
off hand figures of 10%, but nothing that was substantiated with any
kind of legitimate research, or even casual observation.

can anybody prove to help an argument about lv downlighters , can they be
installed in larve and plaster ceilings with fire hoods on  in the uk.
thanks

I have a question regarding radiated immunity tests.
The standard states that the test must sweep from 80MHz to 2.5GHz.
The standard also states that the dwell time needs to be at a least the
sample time of the instrument.  Our instrument has a sample time of 1

Do they have metal-tracks for on the walls, electrical wiring that no longer
uses the box, but has something into which you can plug directly into the
track? I feel i have seen them somewhere?
I am going to have a conpleted house wired that has no electricity, and if

ciao tutti,
ho da proporre un problema di cui non ho ancora letto nulla. Avete
presente un Hard disck? Io sono partito dalle testien di lettura
(sensori MR). NON si riesce a leggere nulla! Poi mi sono accorto che

Hi Group!
Wondering if anyone in the group can explain the difference between a
current rating and a horsepower rating on magenetic starters, disconnect
switches and MCC switch compartments.