Monday, 8 August 2016
Air Conditioners with Inverter technology
Saturday, 16 July 2016
How you can use the 3 phase change over switch in home
For typical domestic use, the device illustrated bellow have two more identical units mounted over a board with some indications regarding the number of phase available and the currently applied change over status.
Similarly the second set of indication lamp is showing the status of the three phases at the outgoing end of the device (Which will be the actual status of the three phases being fed to your home).
whenever there will be an phase outage due to faults or blown fuses at the power distribution feeder end, both sets of same coloured indication lamps will stop glowing to which phase they are assigned for (e.g. if only both sets of Yellow and Blue indication lamps are working that implicates that power supply to Red phase have been disrupted).
And now comes the part where the actual operation of the phase converter/selector will be done. There would be three similar rotary switches with three/four similar markings on it, so lets pick one switch for ease of understanding. Normally, the following would be the positions of the selector switch, for R Phase selection, the knob on switch will be indicating 1 or R. For Y-Phase, the knob will be positioned on 2 or Y and similar for the 3rd of Y phase.
Suppose the Red indication lamps are not working, but other two are working, then the switched have to be adjusted so that only Y and B phase will be supplied further, hence the R-Phase's knob will be rotated and can be placed on either position number 2 or 3 from its earlier position of 1 so that the power line of R phase is connected to that of Y or B-Phase.
So, when the above mechanism is applied, all the 3 indication lamp on the second set will start working although the one indication lamp on the incomer side is still dark, this shows that the changeover have been completed successfully.
Things to remember !!
- Never ever do this change-over operation with your main supply on, in order to avoid a possible flashover, always drop the main MCB of your home before operating the device.
- Never ever use this change over device if you have a direct 3-phase device like flour-mill or water pump of high capacity as the two similar phase will damage the device.
- Always remember to re-position the knobs to its original position once the phase have been restored if the damage caused by heavy flow of current over a single phase have to be avoided.
Thursday, 14 July 2016
Working of tester
- The tester should only be used when you are sure that voltage is within 500 V. Also make sure that proper resistor is connected. Never connect the instrument until you are 100% sure.
- Always use the good quality instrument, you can save a few bucks on low-quality material but it can harm your life.
Tuesday, 12 July 2016
Why don't birds get electrocuted sitting on power lines?
Is it bad to charge your phone over night?
So, is it true? Is charging phone overnight bad?
Well, you’d better ignore that. We couldn’t be more wrong.
And the truth is that Charging phone overnight will not harm your battery in the slightest. Any device with a Lithium Polymer battery must incorporate a charging circuit that will cut off charging power when the battery reaches 100%.
Besides, the smartphone battery is as smart as the phone itself. Apple, Samsung and all the top tech companies, almost of whose products use lithium-based batteries.
Wednesday, 22 June 2016
Magnetic Starter - Control Stations
One of the advantages of magnetic starters is the ability to add control stations. These stations may be located at any convenient location and duplicated as required. The maximum number of stations and their location is unlimited for all practical purposes. Stations are built using Normally Closed (STOP) and Normally Open (START) momentary contact switches. These switches must be rated for the control circuit voltage at a minimum. Over-rated switches will work fine. Many manufacturers incorporate both Normally Open (NO) and Normally Closed (NC) contacts in a single switch body. By rewiring the switch you can change it from one to the other. Many manufacturers also provide interchangeable buttons in at least red and green.
The last station must always be provided to complete the circuit. The intermediate stations may be repeated as many times as required. Suitable 3 conductor control wiring is required from the starter to each of the control stations in turn (daisy chained).
Air Compressor or Float Pump/3ph Starter/1ph Motor
Line Voltage Control Magnetic Starter controlled by a air compressor pressure switch (NC). Includes Auto/Hand/Off control and low oil switch (NC). Both of these are optional and may not be present in all applications. In some cases, the switch will include only Auto/Off. The Auto/Hand/Off is sometimes an integral part of a factory pressure switch. Auto allows for unattended, automatic starting of the compressor when the air pressure in the tank falls below the preset limit. Hand (manual control) allows the pump to be turned on regardless of the position of the pressure switch. This may or may not be appropriate for all applications and is shown in the interest of completeness only. Hand should be used with caution and due consideration to what is happening in the circuit. Off is self explanatory. If no low oil switch is present, merely remove it from the circuit and continue the wires from the start switch back to the coil.
Incidentally, the same circuit can be used to power a sump pump. The float switch (NO) for the sump would be connected in place of the pressure switch. When the switch detects liquid, the contacts will close and the pump motor will start - assuming that the Start Switch is in the Auto position. Hand is obviously desirable in a sump pump application as it allows the pump to be activated even if the float switch is not functioning.
TRANSISTORS
TRANSISTORS A transistor is a semiconductor device that contains three regions separated by two distinct PN junctions. The two junctions are...