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Thread: Load shedding idea

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    Load shedding idea

    What do you think about this?

    An invertor mounted close to the DB which is connected to the lighting circuits only, with a relay coil energised by the mains power. The invertor and batteries could be mounted in the roof above the DB and the lighting circuits run up into a control box. The LED lights could all be 230 volt so that there are no issues with volt drop etc.

    A relay mounted in the DB or in the control box above the DB with the NC contacts used connect to the inverter supply and the NO contacts for the mains supply.

    When there is a power failure or load shedding the relay will switch off but the lights will stay on, powered by the inverter.

    When the power is switched back on again the relay will energise and lights will be fed from the mains supply.

    A stand alone inverter next to the TV for the home entertainment centre and a spare plug for charging stuff etc.

    Gas stove, for cooking, heating ,etc.

    What more do you need.

    Running a generator is no cost effective and is noisy, beside what more do you need.

    By the way a 2 plate gas stove with a 9 kg bottle cost a couple hundred rand and no COC is required, you dont need a R10 000 gas stove with copper piping, COC and oven just to get you thru load shedding.


    Let hear what all the bright sparks have to say about the relay (used as an ATS) in the DB with the inverter.

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    Diamond Member Justloadit's Avatar
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    Hi Ians,

    I have this already.
    Picture here - 500W Inverter
    Click image for larger version. 

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    Brochure on the unit
    Attached Files Attached Files
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    Diamond Member adrianh's Avatar
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    I would love to have the following switch in lin with all my machines, let's call it a 'auto restart lockout'

    If the power is removed from a machine due to load shedding or a trip then I do not want the machine to power up by itself. Many machines such as lasers, cnc's, saws etc. should only by started under human control. When we have a trip or whatever I always go around and turn all the machines off.

    Ok, so the unit should have a plug on the one end and (a) socket(s) on the other. The device has a single pushbutton and lamp. One push to arm, toggle to disarm. The lamp of course lights up when the unit is armed. All that happens is that a one shot pulse latches a relay and also unlatches on next toggle. A nice feature would be for a second lamp to glow if the previous disarm was due to powerloss.

    There is no rocket science to a device like this, maybe a little PIC or AVR and a bit of hardware.

    I think that such devices should be fitted to all outlets in workshops to ensure that no machine could inadvertently turn on by itself. What about the soldering iron that stays on all night, etc.
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    Gold Member daveob's Avatar
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    Quote Originally Posted by adrianh View Post
    I would love to have the following switch in lin with all my machines, let's call it a 'auto restart lockout'

    If the power is removed from a machine due to load shedding or a trip then I do not want the machine to power up by itself. Many machines such as lasers, cnc's, saws etc. should only by started under human control. When we have a trip or whatever I always go around and turn all the machines off.

    Ok, so the unit should have a plug on the one end and (a) socket(s) on the other. The device has a single pushbutton and lamp. One push to arm, toggle to disarm. The lamp of course lights up when the unit is armed. All that happens is that a one shot pulse latches a relay and also unlatches on next toggle. A nice feature would be for a second lamp to glow if the previous disarm was due to powerloss.

    There is no rocket science to a device like this, maybe a little PIC or AVR and a bit of hardware.

    I think that such devices should be fitted to all outlets in workshops to ensure that no machine could inadvertently turn on by itself. What about the soldering iron that stays on all night, etc.
    Adrianh.

    I think I have what you are looking for.

    Was reading a post a while back ( I think it was by Andy ) about the varying voltages when power is restored. Also concerns me as it affects the life span of equipment.

    My device has 3 pin plug, solid state relay ( 40A rating ), and microprocessor.

    When power comes on, the processor checks if the voltage is in the user programmed range ( 170VAC - 180V, 180V - 190V, etc ) and then starts a delay of a user set time ( 1 min, 5 mins, 10 mins, 15 mins, etc up to 2 hours ).

    If the delay is set to '0' then the SSR remains off until the touch button is pressed.

    At the end of the delay, the SSR is activated and the unit goes to sleep until the power is again cut and restored.

    Have been testing on a breadboard for a few days and assembling the PCB tonight.
    Watching the ships passing by.

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    Gold Member daveob's Avatar
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    Actually, come to think of it, it could also be on the power line to your UPS, so can be set to wait 'x' minutes after power is restored before subjecting your PCs to the voltage yo-yo when power first comes back on.

    I have also added an optocoupler so you can link it to your own system to send you an sms when power is cut or restored. The opto will create either an open or closed circuit depending on weather the unit has mains power.
    Watching the ships passing by.

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    Diamond Member AndyD's Avatar
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    Quote Originally Posted by adrianh View Post
    ......I think that such devices should be fitted to all outlets in workshops to ensure that no machine could inadvertently turn on by itself. What about the soldering iron that stays on all night, etc.
    Commercial machines like laser cutters CNC's and saws shouldn't auto restart when power is restored, it's poor and unsafe design if they do, there should always be a requirement for the operator to initiate the start up even after power fail and restore. Small plug-in devices like a soldering station are a bit different
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    Diamond Member adrianh's Avatar
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    Quote Originally Posted by AndyD View Post
    Commercial machines like laser cutters CNC's and saws shouldn't auto restart when power is restored, it's poor and unsafe design if they do, there should always be a requirement for the operator to initiate the start up even after power fail and restore. Small plug-in devices like a soldering station are a bit different
    There is a vast difference between "shouldn't" and reality. Both my lasers have three switches; 1. Power for motion control 2. Power for pumps & fans. 3. Laser power. When the machine restarts after an outage then the following happens; 1. The motion controller homes and moves to its last position, the fans & pumps start & the laser power supply is given power. Now, the laser will not fire but, the motion controller may already have crashed the head.

    A compressor is another example. The machine will happily restart because the power switch is locked on. Many handheld tools have trigger locks that keep the machines powered when the user takes his hand off the trigger. Yes I agree that you have to be a bit doff to leave the lock on the belt sander when you get a trip but the fact remains that the lock will remain in place and start the machine if left in that state.
    How easily someone is offended is directly proportional to how stupid they are.
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    Diamond Member Justloadit's Avatar
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    Quote Originally Posted by adrianh View Post
    Yes I agree that you have to be a bit doff to leave the lock on the belt sander when you get a trip but the fact remains that the lock will remain in place and start the machine if left in that state.
    To avoid this requires forward thinking, unfortunately the majority do not have this ability.
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    Silver Member bones's Avatar
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    i got a gas stove installing a gas water heater next

    but opted for lights you basically charge all the time
    when the power goes out they switch on and is good
    for about 3 to 4 hours depending on the mode the
    one i got has two settings and cost me about R400
    each at a local sale got 30% off they are crap but
    they work a inverter system is expensive

    the cost of the inverter the cost of the batteries
    the cost of the electrician adds up to about R24k
    to R50k the led chargeable lights cost me R400
    each plug them in no big brain required

    i got 4 of them and combined they do a good job but
    as a single unit they are crap but replacing them is
    cheaper then replacing a single battery

    the generator deals with all the heavies so total cost
    R3.5k for the generator and about R2k for the lights
    total cost R5.5k got a powerful laptop if we have to
    work at night

    i saw the same type of lights at Game store for
    about same price give or take R50

  10. #10
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    i wouldnt install the inverter and batteries in the roof space,it is a possible fire hazard.

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