Member postings for Robert Atkinson 2

I was immediaely put off by the fact that you have to sign in before being able to read their terms and conditions. However signing in requires you to agree to the terms an conditions......

Robert.

About 20 years ago the company I worked for threw quite a few Wet and Dry Henry bases and top casings in the skip. We needed a small high flow vacuum pump that could handle a small amount of water to use in a low production product. The Henry motor-fan unit was ideal. We could buy them as spare parts but by the time you bought the motor, rubber mounts, and brackets it came to more than a complete new Henry from Argos. The tools and hoses went to local charity shops but we never found a use for the bases....

I was just about to say legitimate. Even as a UK resident I've received USA class action settlement payments for items I'd bought in the US and registered. These included one from Sony when they dropped their e-reader range.
I hope somone starts a class action against Western Digital for their My Cloud Home for wich they had a hack causing loss of access and have also dropped support to them. Dispite the fact they arn't supported they are still for sale.

Robert.

Oops yes. Should be UNEF (UN Extra Fine)

UNF and UNS are technically different but many suppliers use them interchagably for fine threads. For example 3/8-32 is a common thread in electrical items. I have seen this quoted as both UNF and UNS by component and tap / die suppliers.

Robert.

Yes that is the motor.

The low power for size is due to the low speed and lack of fan cooling. Running it on a VFD Would let you take it to 400Hz / 3600RPM. The rotor bearing limit foe 100m would seem to be 6000RPM according to page 9 of this https://library.e.abb.com/public/367c91cdc1dee017c1257b130057111e/Catalogue%20GenPurpMotors_GB_12_2004%20RevA.pdf

With a VFD this motor would happily drive a small lathe like a myford ML without using a lay-shaft or high reduction belt drive.

Robert.

Does it have a rating plate?

It could be a high pole count motor, 6 or even 8 pole. It could also be designed for use on an inverter.

The grease does look a bit dried out. Of course the race should not be packed full or the grease will churn and overheat.

Robert.

That is just standard screened 3 core + earth 3 phase screened cable. It's not the VFD special triple earth shown here:
https://inverterdrive.com/group/AC-Motor-Power-Cables/3-Phase-symmetrical-shielded-EMC-motor-cable-2m/

If that is what you ordered you need to have a word with the supplier. They might have been given the wrong cable.

Robert.

Edited By Robert Atkinson 2 on 01/07/2023 13:19:06

The modification labels are a standard part. RS used to sell them but seem to have stopped. They are available elsewhere e.g. https://www.labelsource.co.uk/label/labels-tags---nameplates/general-and-industrial-labels/modification-labels

The manual does not show the actual image sensor resolution. It is probably 640x480 Not the 500 million pixels claimed by the adverts. The fact that it is colour immediately tells me it is not optimised for night vision with IR illumination. Assuming it has no IR block filter (there is no control for a day/night filter), being a colour sensor immediately puts it at a disadvantage for both day and night. The lack of IR filter reduces sharpness in daylight due to IR wavelengths being out of focus. At night the colour matrix on the CCD reduces the IR sensitivity.
I'd send it back. Look for a used Sony digital camcorder with "Nightshot" this will work much better as it has a movable IR filter. Bit of info here:
https://laserpointerforums.com/threads/why-sony-nightshot-diy-night-vision-here.71151/

Robert.

The US domestic electrical supply is very similar to the UK 110V tool system. It is twice the voltage of the UK safety sytem. Domestic premises in the USA are typicall provied with a split phase 115V - Neutral - 115V with the neutral connected to ground. The two 115V supplies are 180 degrees out of phase so there is 230V between them. Heavy loads such as water heaters, air conditioning and washing machines are 230V and connect across the two phases.

Robert.

A fuseholder carrying above 50V that can be undone without using a tool or removing a separate cover first does not meet current electrical standards.

Robert.

You may have to re-focus the objective lens and use a IR block filter to get the same sharpness as IR only. IR and visble light focus at different points.
However it is likely that this is just low resoluton. What does the specfication say for the sensor resolution.

M3.5 is interchangable with 4BA. This non-preferred size is used in the UK for commonality with older electrical fittings. Availble from any hardware or electrical supplier.

Robert.

I hope you will have filters on both the fan and compressor inlet. Putting a dust generator on a vacuum pump has it's disadvantages...

As a change from the usual Spitfires practicing over the village I just had the dead sparrows Red Arrows go almost directly overhead at fairly low level while I was firing up the barbeque.

Contact or electrical continuity do not make an adequate RF shield. additionally the material may have coatings. From practical experience with flexable conduit designed for electrical applications I know it does not work as an EMI screen. In the UK at least it is not permitted to use flexible conduit as an earth conductor. (BS7671 543.2.4 ). This video explains https://www.youtube.com/watch?v=1Wn7Xt8JAzQ If it not good enough as a power earth it cetainly won't work at RF.

Macolm,
Nothing personal, but you appear to have little knowlege of VFDs. You MUST NOT connect capacitors across the motor output of a VFD (unless the manufacturer specfically says otherwise). The output of a typical VFD is a series of high frequency pulses. Connecting a capacitor across the output will cause excessive current and probable destruction of capacitors and VFD. If output filtering is required it must be inductive. A simple ferrite sleeve can help with high frequences. Thes can be pplied without too much concern. For lower frequencies a inductor is required in each line. These are often called "reactors" by VFD manufacturers. You need to follow the mnufacturers guidelines when selecting them. They also need higher voltage insulation than you might expect due to the high dI/dt.
Simplified explanations of EMI/EMC are not adequate for complex systems like VFDs.

Robert.

Macolm,
While you comments are not wrong, they do not really apply to Rodgers specfic case of a VFD motor connection.

Robert.

Indeed. I was once asked to look at the electrical supply for a pump being fittted to an aircraft. It was to pump fuel from a belly tank to a high wing tank. The pump was in the wing. I was not popular when I pointed out that at cruise altitude there was not enough air pressure for it to work. The highly qualified system designer did not realise that it the pump only created a vacuum and air pressure pushed the fuel up the pipe. He didn't belive me but I attended a meeting with the pump supllier who promply said their product would not work when he was shown the concept drawing. They ended up with a pump in the belly tank. I also pointed out that on a hot day the fuel would "boil" if they tried to lift it by vacuum. They then realised that while I was employed s a Avionics designer I was also experiened and qualified on fuel systems.....

Robert.

Edited By Robert Atkinson 2 on 24/06/2023 19:13:12