Motion detector

Van Chocstraw Inscribed thus:

Outdoors, thats always a possibility. I thought IP35 was supposed to be splash proof !

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Best Regards:
                     Baron.

o

t,

Actually, it produces no 'billable' power consumption, but it eats power throughout the distribution system in cable and transformer losses. Thus, reactive losses, especially inductive losses, are discouraged by the utilities companies.

As Phil has pointed out, and you have conceded, the PFs are different, and I was clearly focussing on power, not current.

Sylvia.

"Robert Macy" "Phil Allison" > "Trevor Wilson"

Actually, it produces no 'billable' power consumption, but it eats power throughout the distribution system in cable and transformer losses.

** Really ??

The largest " I squared R " copper loss will be where the largest resistance exists in the AC supply.

Typical domestic AC outlets have internal resistances of about 0.2 to 1 m - mostly due to the wiring installed in the premises. Resistances values further back in the supply system are very much lower.

A suppression cap draws only about 3.5mA from a 240 volt AC supply.

So the loss in watts is between 2 and 12 uW - that is MICRO watts !!!

Absolutely SFA.

Piss off - you pedantic fool.

.... Phil

**As was I. The POWER consumed by the device using a relay will probaby be significantly higher than if it uses a TRIAC. The reason is that the current flowing through the load will be much higher with a relay.

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Trevor Wilson
www.rageaudio.com.au

It might be, but it's not the power consumed by the load that is the main concern. It is the power consumed by the switching element, since it is where most of the voltage drop occurs. The TRIAC is essentially resistive, so it is consuming real power. The relay, with a capacitor across its contacts, is only consuming reactive power, for which there is no charge to a retail customer.

Sylvia.

**Yes, it is.

It is the power consumed by the switching element, since

**Change of discussion, duly noted. There will be a Voltage drop across any semiconductor, whilst there will be essentially zero drop across relay contacts. THAT, however, is not your original contention.

The TRIAC is essentially

**Wrong. The TRIAC is essentially a solid state switch. It does, however, dissipate some power, due to the valtage drop across the device. A relay (usually) exhibits a far lower Voltage drop.

The relay, with a capacitor

**WRONG! The capacitor across the contacts allows a small current to flow into the load at all times. This power will certainly be charged to the consumer. A TRIAC, OTOH, will usually allow a much smaller current to flow into the load. Thus, the consumer will pay less.

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Trevor Wilson
www.rageaudio.com.au

Remember, we're talking about the off state. The voltage drop across the device is the input voltage, near enough.

Your ignoring the power dissipated in the TRIAC. That's most of the power consumption of the combined system in the off state.

Sylvia.

**Correct. Since the off state of a TRIAC exhibits a leakage current in the order of a few microAmps, it is several orders of magnitude less than the current flow through a typical suppression cap across relay contacts. **Well, no, I'm not. The Pdiss is miniscule in the off state.

That's most of the

**Yes, it is. It is also far less than the Pdiss of the load, when using a relay. The TOTAL power consumption of a TRIAC device (when connected to the load) is generally lower than a relay device.

--
Trevor Wilson
www.rageaudio.com.au

Leakage figures vary.

The issue I was raising was the power consumption in the off state. You may be right in asserting the relays require more power than TRIACS in the one state, but that means that one would need to consider the duty cycle to reach a conclusion. It seems that a motion detector system would spend most of its time in the off state.

Sylvia.

Maybe I am miss reading your statement how ever, if I understand you correctly, I think you have a misconception with the operation of thyristors.

To enable a thyristor in the on state, it still requires less power with the added components than what a relay would require considering that a relay needs to power it's coil(constantly). The operation of a coil will use more energy than maintaining a thyristor in the on state.

And for it being off, leakage is far less than you think. Energy being lost in the thyristor is minuscule. You'll have more loss from heat of a relay coil.

...snip...

nce

ances

My favorite film!, but the quote is, "...pedantic old fool..."

Hmm, 1500W room heater drops the voltage from 125 to 119, implying resistance of around 0.48 ohms. Assuming wiring is either 12 Awg at

1.6 ohms/kft, or 14 Awg at 2.5 ohms/kft that means there was 150 [300 total out and back], or 81 ft of run to that 'low resistance' feed. Expecting 0.2 to 1 ohm seems reasonable.

I remember 'green standby is less than 1 W', or 10 mA, so 3.5 mA is less, and not power. The loss inside residences would be on the order of 6 uW. If everybody had 5 of these and 10million people did this [not including businesses], that would only amount to 300 watts TOTAL. There is MUCH more than that lost along the transmission paths delivering primary power, interestingly low.