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In ELECTRONIC CIRCUITS, the capacitor tolerance can be determined by a code that appears on the casing. The code is a letter that often follows a three-digit number (such as 130Z).The first two are the 1st and 2nd significant digits and the THIRD is a multiplier code. Most of the time the last digit TELLS you how many zeros to write after the first two digits and these are READ as Pico-Farads.

In electronic circuits, the capacitor tolerance can be determined by a code that appears on the casing. The code is a letter that often follows a three-digit number (such as 130Z).The first two are the 1st and 2nd significant digits and the third is a multiplier code. Most of the time the last digit tells you how many zeros to write after the first two digits and these are read as Pico-Farads.

A lock-out relay is generally placed in LINE before or after the e-stop switch so the power can be shut off at one central location. This relay is powered by the same ELECTRICAL source as the control power and is operated by a KEY lock switch. The relay itself may have up to 24 contact points WITHIN the unit itself. This allows the control power for multiple machines to be locked out by the turn of a SINGLE key switch.

A lock-out relay is generally placed in line before or after the e-stop switch so the power can be shut off at one central location. This relay is powered by the same electrical source as the control power and is operated by a key lock switch. The relay itself may have up to 24 contact points within the unit itself. This allows the control power for multiple machines to be locked out by the turn of a single key switch.

Only one of the terminals is evident in the earth RESISTANCE. In order to find the second TERMINAL we should recourse to its definition: Earth Resistance is the resistance existing between the ELECTRICALLY accessible PART of a buried electrode and another point of the earth, which is far away.

The resistance of the electrode has the following components:

1. the resistance of the metal and that of the CONNECTION to it.
2. the contact resistance of the surrounding earth to the electrode.

Only one of the terminals is evident in the earth resistance. In order to find the second terminal we should recourse to its definition: Earth Resistance is the resistance existing between the electrically accessible part of a buried electrode and another point of the earth, which is far away.

The resistance of the electrode has the following components:

Isolator is a off load device which is used for isolating the downstream circuits from UPSTREAM circuits for the REASON of any maintenance on downstream circuits. it is manually OPERATED and does not contain any solenoid unlike circuit breaker. it should not be operated while it is having load. FIRST the load on it must be made zero and then it can safely operated. its specification only rated current is given. But circuit breaker is onload automatic device used for breaking the circuit in CASE of abnormal conditions like short circuit, overload etc., it is having three specification 1 is rated current and 2 is short circuit breaking capacity and 3 is instantaneous tripping current.

Isolator is a off load device which is used for isolating the downstream circuits from upstream circuits for the reason of any maintenance on downstream circuits. it is manually operated and does not contain any solenoid unlike circuit breaker. it should not be operated while it is having load. first the load on it must be made zero and then it can safely operated. its specification only rated current is given. But circuit breaker is onload automatic device used for breaking the circuit in case of abnormal conditions like short circuit, overload etc., it is having three specification 1 is rated current and 2 is short circuit breaking capacity and 3 is instantaneous tripping current.

Different losses that occur are:

• Forward conduction losses during conduction of the thyristor
• Loss due to LEAKAGE current during forward and REVERSE BLOCKING.
• Power loss at gate or Gate TRIGGERING loss.
• Switching losses at turn-on and turn-off.

Different losses that occur are:

Thyristor can be triggered by increasing the forward VOLTAGE between anode and cathode, at forward break over voltage thyristor starts conducting. HOWEVER this PROCESS may damage the thyristor, so thyristor is advices to trigger on through the gate PULSE. When a gate signal is applied thyristor turns on before REACHING the break over voltage. Forward voltage at which the thyristor triggers on depends on the magnitude of the gate current. Higher is the gate current lower is the forward break over voltage.

Thyristor can be triggered by increasing the forward voltage between anode and cathode, at forward break over voltage thyristor starts conducting. However this process may damage the thyristor, so thyristor is advices to trigger on through the gate pulse. When a gate signal is applied thyristor turns on before reaching the break over voltage. Forward voltage at which the thyristor triggers on depends on the magnitude of the gate current. Higher is the gate current lower is the forward break over voltage.

During the triggering process of the thyristor from forward blocking STATE to forward CONDUCTION state through the GATE signal, by applying the gate signal (voltage between gate and cathode) increases the minority carrier density in the p-layer and THEREBY facilitate the reverse break over of the junction J2 and thyristor starts conducting. Higher the magnitude of the gate current pulse, LESSER is the time required to inject the charge and turning on the scr. By controlling the amount of charge we can control the turning on time of the scr.

During the triggering process of the thyristor from forward blocking state to forward conduction state through the gate signal, by applying the gate signal (voltage between gate and cathode) increases the minority carrier density in the p-layer and thereby facilitate the reverse break over of the junction J2 and thyristor starts conducting. Higher the magnitude of the gate current pulse, lesser is the time required to inject the charge and turning on the scr. By controlling the amount of charge we can control the turning on time of the scr.

When scr is conducting CURRENT in forward conduction state, scr will RETURN to forward blocking state when the anode current or forward current falls below a low level called Holding current Note: LATCHING current and Holding current are not same. Latching current is associated with the turn on PROCESS of the scr whereas holding current is associated with the turn off process. In general holding current will be slightly LESSER than the latching current.

When scr is conducting current in forward conduction state, scr will return to forward blocking state when the anode current or forward current falls below a low level called Holding current Note: Latching current and Holding current are not same. Latching current is associated with the turn on process of the scr whereas holding current is associated with the turn off process. In general holding current will be slightly lesser than the latching current.

Gate signal is to be applied to the thyristor to trigger the thyristor ON in safe MODE. When the thyristor starts CONDUCTING the FORWARD CURRENT above the minimum value, called Latching current, the gate signal which is applied to trigger the device in no LONGER require to keep the scr in ON position.

Gate signal is to be applied to the thyristor to trigger the thyristor ON in safe mode. When the thyristor starts conducting the forward current above the minimum value, called Latching current, the gate signal which is applied to trigger the device in no longer require to keep the scr in ON position.

SCR or THYRISTOR will have three regions of operations based on the mode in which the device is connected in the circuit.

Reverse blocking region: When the CATHODE of the thyristor is made positive with respect to the anode and no gate signal is applied. In this region scr exhibits the reverse blocking characteristics similar to diode.

Forward blocking region: In this region the anode of the thyristor is made positive with respect to the cathode and no gate signal is applied to the thyristor. A small leakage current flow in this mode of operation of the thyristor.

Forward conduction region: when the forward VOLTAGE applied between the anode and cathode increases at particular break over voltage avalanche breakdown takes place and thyristor starts CONDUCTING current in forward direction. By this type of TRIGGERING the device damages the scr. Hence a gate signal is applied before the forward break over voltage to trigger the scr.

SCR or thyristor will have three regions of operations based on the mode in which the device is connected in the circuit.

Reverse blocking region: When the cathode of the thyristor is made positive with respect to the anode and no gate signal is applied. In this region scr exhibits the reverse blocking characteristics similar to diode.

Forward blocking region: In this region the anode of the thyristor is made positive with respect to the cathode and no gate signal is applied to the thyristor. A small leakage current flow in this mode of operation of the thyristor.

Forward conduction region: when the forward voltage applied between the anode and cathode increases at particular break over voltage avalanche breakdown takes place and thyristor starts conducting current in forward direction. By this type of triggering the device damages the scr. Hence a gate signal is applied before the forward break over voltage to trigger the scr.

Fuses MUST be rated for the voltage AC or DC in which they will be used. Generally, fuses have a DC voltage rating that is HALF of the MAXIMUM AC voltage rating.

Fuses must be rated for the voltage AC or DC in which they will be used. Generally, fuses have a DC voltage rating that is half of the maximum AC voltage rating.

1. VOLTAGE SOURCE INVERTER
2. CURRENT Source Inverter

A DEVICE which converts dc power into AC power at desired output VOLTAGE and frequency is called as Inverter.

A device which converts dc power into ac power at desired output voltage and frequency is called as Inverter.

It is the one which CONVERTS FIXED alternating VOLTAGE to a variable voltage without CHANGE in frequency.

It is the one which converts fixed alternating voltage to a variable voltage without change in frequency.

It is the CONVERTER WHOSE OUTPUT FREQUENCY is more than the INPUT frequency.

It is the converter whose output frequency is more than the input frequency.

It is the converter WHOSE output FREQUENCY is LESS than the INPUT frequency.

It is the converter whose output frequency is less than the input frequency.

STEP up cyclo-converter
Step down cyclo-converter.

Step up cyclo-converter
Step down cyclo-converter.

It is also known as frequency changer. It converts input POWER at one frequency to output power at ANOTHER frequency with one stage CONVERSION.

It is also known as frequency changer. It converts input power at one frequency to output power at another frequency with one stage conversion.

The input power FACTOR is IMPROVED.It PREVENTS the OUTPUT voltage from becoming negative.Load current waveform is improved.

The input power factor is improved.It prevents the output voltage from becoming negative.Load current waveform is improved.

The PROCESS of changing the direction of CURRENT flow in a particular path of the CIRCUIT. It is USED to turn off the SCR.

The process of changing the direction of current flow in a particular path of the circuit. It is used to turn off the SCR.

The ANGLE between the zero CROSSING of the INPUT voltage and the instant the SCR is fired is called as DELAY angle or FIRING angle.

The angle between the zero crossing of the input voltage and the instant the SCR is fired is called as delay angle or firing angle.

When gate current is several times HIGHER than the REQUIRED gate current, the SCR is said to be HARD fired.It reduces the turn on TIME. and enhances the di/dt capability.

When gate current is several times higher than the required gate current, the SCR is said to be hard fired.It reduces the turn on time. and enhances the di/dt capability.

The snubber circuit is used for the dv/dt PROTECTION of the SCR. It is a SERIES COMBINATION of a resistor and a capacitor in PARALLEL with the SCR.

The snubber circuit is used for the dv/dt protection of the SCR. It is a series combination of a resistor and a capacitor in parallel with the SCR.

FORWARD voltage TRIGGERING
GATE Triggering
dv/dt triggering
Temperature triggering
Light triggering

Forward voltage triggering
Gate Triggering
dv/dt triggering
Temperature triggering
Light triggering

It is the minimum current required to LATCH(turn on) the SCR from FORWARD blocking STATE to forward CONDUCTION state.

It is the minimum current required to latch(turn on) the SCR from forward blocking state to forward conduction state.

It is the MINIMUM current required to hold the SCR in forward CONDUCTION state. When the forward current becomes LESS than holding current, SCR TURNS from forward conduction state to forward blocking state.

It is the minimum current required to hold the SCR in forward conduction state. When the forward current becomes less than holding current, SCR turns from forward conduction state to forward blocking state.