Measuring motor insulation using HI POT tester

What is HI-POT tester?
When we need to evaluate motor condition,HI-POT tester or High Potential tester is the common equipment are used.As we know,a multimeter or ohm meter reading only can determine if a motor winding is open or shorted but cannot checked winding insulation condition if shorted with ground or phase.

The main purpose of the Hi Pot tester is to verify the quality and integrity of the electric motor insulation materials used on the armature or stator and also safe to using it without any defect.
Sometime we not take a serious attention or not know about it to checked winding insulation.This step is important to ensure motor can running in good condition without any breakdown.
Normally electrical motor may have a weakened winding that shorts to ground when it running.It have several caused for the winding breakdown due to the value of system voltage,winding heat build up or overloaded mechanical stress.For other caused it will come from motor terminal board that has an insulation failure from the terminal to ground (earth) or from other terminal for winding connection.

Basic operation of HI-POT Tester
A HI-POT tester produce power source with a high voltage (Volt) and low current (ampere) and it is used to check for an insulation failure for motor winding that the ohmmeter cannot measure with its low voltage power source may miss.
It measures winding insulation resistance to ground (earthing) and terminal board resistance from terminal to ground and from terminal to terminal ( phase to phase )
To get a best result and for safety reason when perform measurement for winding insulation resistance,all wiring is removed from the motor winding terminals.It also same when perform measurement for terminal board resistance, all wiring is removed from the terminal board.
Below is several rules when using the Hi-Pot tester.It is to avoid any serious damage or injuries during insulation measurement and should never be :

1. Operated alone or by an inexperienced service person.
2. Set at a voltage of more than twice the motor operating voltage plus 1000 volts.
3. Be set for more than 5 milliamps without consulting or refer user manual from motor manufacture
4. Applied for more than the time it takes to obtain a reading (no more than a few seconds).
5. Used as a phase-to-phase winding check.
6. For air condition motor compressor,used when the system is in a vacuum.

* SAFETY NOTE : Please read HI-POT tester user manual before using it and refer to the trained or qualified person for assist during measurement.It the best way to avoid any unexpected issued and for safety reason.

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Pedal Generator Projects

Why pedaling for electricity ?

Know the cost of one KWh as your electricity company sells it ? It's EUR
0.23 in my place and earning this through pedal power would take me 10
hours. Not much of an incentive to think about pedal generators. Still
the need for pedal power generation seems to exist, as frequent e-mail
requests tell me. Well, pedal power can be made available anywhere, it
requires no fuel, is available both day and night, the equipment is
inexpensive and needs almost no maintenance.

This page addresses two key use cases:

1. Charging batteries for small, portable devices while traveling on a bicycle
2. Generating as much electrical power as possible on a stationary pedal generator

Low power battery charging

This project fits a travel bike that will be taken to remote locations
with no electricity. The user will be able to charge NiMH batteries for
light, communication, navigation and entertainment equipment, utilizing
the energy from the bike's standard 6V/3W dynamo. While riding, up to 6W
of electrical power are available to the charger (not a mistake, it is
about twice the rated dynamo power).

A switch selects either the light system,
the battery charge mode or OFF. In charge mode, the rectified dynamo
current is driven through a string of series-connected NiMH cells. At
moderate riding speed, one to 10 cells can be charged at once. The
current is typically 500mA and decreases somewhat as cell count
increases. The ammeter displays the charge current, so it's easy to see
if cells charge correctly and at the expected current.

All 4 diodes are 1N5402 (or 1N5404 through 1N5408). Alternatively, use
1N4003 through 1N4007 (lower current capability, higher chance of damage
if reversing battery polarity).

If individual cells will be charged, an appropriate battery box is
needed. A jumper cable makes the box adapt to fewer cells. It's
acceptable to mix different types of cells; they will all be charged at
the same current.

The circuit withstands operation without batteries connected. Batteries
may remain attached to the circuit permanently, none of the modes
produces a leakage current that discharges the cells. One weak point of
the circuit is wrong battery polarity: This could fry the diodes and the
ammeter. If batteries are likely to be reversed, a fuse should be added
in line with the ammeter.

There is no end-of-charge indication as this would be unreliable with
the fluctuating supply of a dynamo. Not a problem, cells get time to
relax and cool down as the bike stops from time to time. With the rider
being right there with his sense of time and his temperature probe
finger, it's highly unlikely that batteries get forgotten and "cooked"
for many hours. Much unlike cheap mains-powered chargers that overcharge
NiMH cells by design - and still the cells last quite a while.

Stationary pedal generator / high power battery charging

This project is capable of providing basic electricity to a remote
location where solar panels are not practicable. While pedaling, up to
300W are available (40 ..150 continuously, depending on rider).

The Internet holds a lot of suggestions on how to build a pedal-powered
electrical generator. Now what has put ME off is that all these
solutions require odd parts that are hard to come by and / or demand a
lot of mechanical work in adapting a motor / generator to a bicycle. The
end product often suffers from friction, belt slip and rapid wear.

With the popularity of electric bicycles on the rise, the pedal
generator builder's life has become easier: Today we have a good variety
of bicycle hub motors, many of these made in Chinese factories and
often being sold for less than EUR 100. These motors carry magnets on
the rotor while the copper windings are on the stationary part. They are
perfect dynamos !

Selecting the right motor

• The motor will be driven on a stationary bike, so has to be a rear
  hub motor (front wheel of stationary bike obviously not being driven)
• For good efficiency, the motor should employ state-of-the-art rare-earth permanent magnets and it should be brushless
• To achieve the best flywheel effect, the motor should be heavy and put in a wheel
• To minimize mechanical losses, the motor should be direct drive / not use internal gears
• To cope with the power of a physically-fit pedaler for longer
  periods of time, the motor should be rated for at least 200W, more is
  better (reduces losses, increases weight)
• The voltage of the motor should exceed the desired output voltage,
  so that there's useful output even when not pedaled full-steam

The picture shows the guts of the motor that I've picked. It's a 24V,
500W rear hub motor made by Golden Motor / Jiangsu and it will charge a
12V battery for me.

The mechanical setup

1. Find a bicycle to use - it can be any piece of junk but it needs a
   working BB, pedals, chain, a saddle and ideally a rear derailleur
2. Replace the rear wheel with the hub motor
3. Put the bike on a stand so that the rear wheel can spin freely (some
   older Durch or Chinese pannier racks incorporate a stand that will work
   nicely). Alternatively suspend the tail of the bike so that it just
   doesn't touch the ground.
   
   I myself have built a stand from metal brackets mounted on a wooden base.

Restoring the bike to its original condition is fast: Remove from stand and swap the wheel back.

The electrical circuit

Input is the motor / generator on the left of the schematic, output
( 12V-) is on the very right. Any load could be connected to the output:
Light bulbs, fluorescent ballast, LED lighting fixtures, radio, cell
phone charger, TV

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Honda CB750C CB750K and CB750K LTD Motorcycle Electrical Circuit Diagram

This is an electrical wiring diagram for the Honda CB750C, CB750K, and CB750K-LTD motorcycle. This is a wiring diagram that comes in a color mode that shows every connection in different wire colors.

Honda CB750C, CB750K, and CB750K-LTD Motorcycle Electrical Circuit Diagram

There are many components will be shown here, you will see parts like: battery, license plate light, tail & brake light, alternator, ignition coils, plugs, neutral switch, oil pressure switch, spark units, engine stop switch, etc. You can also see a diagram key that explain about the wiring connections. As for the cables, you can see that they are already shown in many different colors to make it easier to distinguish them from one another.

You can use this circuit diagram to do troubleshooting job you might have with your motorcycle, or if you want to assembly a new part. Save this circuit diagram in your PC for free in case you might need them again one day, just right click on image, choose save image as, choose saving location, and save. Work safe and enjoy.

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TV Remote Control Jammer

This is really fantastic circuit.Because you can fun with this circuit.If others operate your TV set or setup you can use this to control them.and you can use this to annoy someone.so enjoy with this.
Parts:

Q1 2N4403 PNP Transistor
Q2 2N4401 NPN Transistor
C1 10nF Ceramic Disc Capacitor
C2 1uF Electrolytic Capacitor
D1, D2, D3 High Output IR LED
R1 100K 1/4W Resistor
R2 150K 1/4W Resistor
R3 10K 1/4W Resistor
R4 1K 1/4W Resistor
S1 Normally Open Momentary Push Botton
B1 4.5V Battery (Three "AA"s In Series)
MISC Wire, Case, Board

Note
# You may need to adjust the value of R5 for the right frequency.
#supply 4.5v

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Low cost fire alarm circuit

When there is a fire breakout in the room the temperature increases.This ultra compact and low cost fire alarm senses fire breakout based on this fact.
Transistor BC177 (Q1) is used as the fire sensor here.When the temperature increases the leakage current of this transistor also increases.The circuit is designed so that when there is an increase in the leakage current of Q1 ,transistor Q2 will get biased.As a result when there is a fire breakout the transistor Q2 will be on.The emitter of Q2 (BC 108)is connected to the base of Q3(AC 128).So when Q2 is ON Q3 will be also ON.The transistor Q3 drives the relay which is used to drive the load ie,light,bell,horn etc as an indication of the fire.The diode D1 is used as a free wheeling diode to protect it from back EMF generated when relay is switche

Notes.

* The Preset R1 can be used to desired temperature level for setting the alarm ON.
* This is not a latching alarm,ie;when the temperature in the vicinity of the sensor decreases below the set point the alarm stops.
* The circuit can be powered using a 9V battery or a 9V battery eliminator.
* All capacitors are electrolytic and must be rated at least 10V.
* The load can be connected through the C,NC,NO points of the relay according to your need.
* The calibration can be done using a soldering iron,and a thermo meter.Switch ON the power supply.Keep the tip of soldering iron near to the Q1.Same time also keep the thermometer close to it.When the temperature reaches your desired value adjust R1 so that relay gets ON.Done!

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Blinking Arrow

A blinking arrow can be a very attractive gadget, suitable for many indication purposes. This circuit provides a bar-mode sequencer driving 17 LEDs arranged in four groups in order to build-up a bright arrow. When the build-up of the arrow is completed, all LEDs stay on for some time, then off for the same time-delay and then the cycle restarts. Sequence speed can be set by R1

Parts:

R1_____________500K 1/2W Trimmer
R2______________22K 1/4W Resistor
R3,R5,R7,R9_____10K 1/4W Resistors
R4,R6,R8,R10_____4K7 1/4W Resistors
R11,R12,R13____470R 1/4W Resistors
R14____________270R 1/4W Resistor

C1_______________4µ7 25V Electrolytic Capacitor
C2_____________220µF 25V Electrolytic Capacitor

D1--D17________LEDs Any type and color (except blue and white, see Notes)

Q1,Q2,Q3,Q4___BC337 45V 800mA NPN Transistor

IC1____________4093 Quad 2 input Schmitt NAND Gate IC
IC2____________4520 Dual binary up-counter IC
IC3____________4094 8-stage shift-and-store bus register IC

For those wishing to experiment, sequence timings can also be varied by connecting pin #5 of IC1B to pin #5 of IC2 and pins #6, 8 and 9 of IC1 to pin #6 of IC2. Other pin combinations are possibile by shifting the above named pins of IC1 to higher outputs of the counters contained in IC2, i.e. pins #6 and 11, pins #11 and 12 etc.
The resulting effect of the original four groups of 17 LEDs arrangement is shown in the title heading.
Notes:

* Obviously, many different arrangements using more or less LEDs are possibile.
* At 12V supply the maximum number of LEDs per strip is that shown in the circuit diagram, when red LED types are used. Yellow, green and orange types may require a lower value of the limiting resistors or a lesser number of devices per strip.
* Please note that the unused section of IC1 must have the inputs tied to negative ground whereas the output must be left open, as shown at the bottom of the diagram.

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AM Transmitter

Notes:
It is illegal to operate a radio transmitter without a license in most countries. This ircuit is deliberately limited in power output but will provide amplitude modulation (AM) of voice over the medium wave band.
The circuit is in two halfs, an audio amplifier and an RF oscillator. The oscillator is built around Q1 and associated components. The tank circuit L1 and VC1 is tunable from about 500kHz to 1600KHz. These components can be used from an old MW radio, if available. Q1 needs regenerative feedback to oscillate and this is achieved by connecting the base and collector of Q1 to opposite ends of the tank circuit.

The 1nF capacitor C7, couples signals from the base to the top of L1, and C2, 100pF ensures that the oscillation is passed from collector, to the emitter, and via the internal base emitter resistance of the transistor, back to the base again. Resistor R2 has an important role in this circuit. It ensures that the oscillation will not be shunted to ground via the very low internal emitter resistance, re of Q1, and also increases the input impedance so that the modulation signal will not be shunted. Oscillation frequency is adjusted with VC1.
Q2 is wired as a common emitter amplifier, C5 decoupling the emitter resistor and realising full gain of this stage. The microphone is an electret condenser mic and the amount of AM modulation is adjusted with the 4.7k preset resistor P1.
An antenna is not needed, but 30cm of wire may be used at the collector to increase transmitter range

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