0
Want this question answered?
Be notified when an answer is posted
Add your answer:
Earn +20 pts
Why current transformers are required in protective relaying scheme?
Current transformers (CTs) are used to monitor the current (or lack of) in high-voltage systems, and their secondary outputs controls the behaviour of protection-system relays. The CTs (1) reduce the current to values that match the current ratings of the protective relays, and (2) electrically-isolate the relays from the high-voltage system.
What is the pt transformer?
The abbreviation, 'PT', stands for 'potential transformer' (in Britain, the abbreviation is 'VT', and stands for 'voltage transformer'). This, together with a 'current transformer', falls into a category of transformer known as 'instrument transformers'. A 'PT' or 'VT' is used to reduce a high voltage to a level of voltage that can be safely read, remotely, by regular a.c. voltmeters or to provide inputs to high-voltage protection relays, while electrically- isolating the secondary circuit from the high-voltage primary circuit for the purpose of safety.
What condition the relays should be use in power voltage?
Inorder to achieve the impedance maching ....
What are the three kinds of switching mechanism used in low voltage?
Transistors, relays, and triacs.
What are the advantages of instrument transformer?
'Instrument transformer' is the collective name for current transformers (CTs) and voltage (or 'potential') transformers (VTs/PTs). These transformers have two functions:to reduce the current or voltage in a high-voltage primary circuit to values that may be measured using regular ammeters or voltmeters ('burdens'), or to provide the current or voltage inputs to protection relays.to electrically-isolate their secondary burdens from the high-voltage primary circuit for the purpose of safety.
Do relays use high voltage to control low currant circuits?
Low voltage to operate relay controlling high CURRENT circuits (currant is a dried fruit).
Why current transformers are required in protective relaying scheme?
Current transformers (CTs) are used to monitor the current (or lack of) in high-voltage systems, and their secondary outputs controls the behaviour of protection-system relays. The CTs (1) reduce the current to values that match the current ratings of the protective relays, and (2) electrically-isolate the relays from the high-voltage system.
What is an instrument transformer?
An 'instrument transformer' is a category of transformer used to supply measuring instruments or protective relays. There are two types of instrument transformer: a 'voltage transformer' (known as 'potential transformer' in North America), and a 'current transformer'. They are used with high-voltage systems, where it is hazardous to connect instruments directly to such systems.Voltage tranformers are used to reduce high-voltages down to a level that can be safely applied to voltmeters, or to the voltage-coils of wattmeters or energy meters, or to protective relays, while electrically-isolating those instruments (and personnel) from the high-voltage supply.Current tranformersare used to reduce high-voltage currents down to a level that can be safely applied to ammeters, or to the current-coils of wattmeters or energy meters, or to protective relays, while electrically-isolating those instrument (and personnel) from the high-voltage supply.
How are relays safe?
Relays can be considered safe when used for remote switching. It only takes a small, low voltage current to activate a relay, which can then switch a high voltage, high current supply. There is no electrical connection between the coil and contacts. So switching dangerous voltages can be done at a distance, without anyone getting near the dangerous voltages.
What is the pt transformer?
The abbreviation, 'PT', stands for 'potential transformer' (in Britain, the abbreviation is 'VT', and stands for 'voltage transformer'). This, together with a 'current transformer', falls into a category of transformer known as 'instrument transformers'. A 'PT' or 'VT' is used to reduce a high voltage to a level of voltage that can be safely read, remotely, by regular a.c. voltmeters or to provide inputs to high-voltage protection relays, while electrically- isolating the secondary circuit from the high-voltage primary circuit for the purpose of safety.
Which starting system component uses a small amount of current to control a large amount of current?
I think its a starter solenoid or a relay. I know relays take high voltage current to power low voltage circuits. Hope that helps..
What are the uses of instrument?
The term, 'instrument transformer', is applied to current transformers and voltage transformers (known, in North America, as 'potential Transformers'). The primary windings of instrument transformers are connected to high-voltage systems, and their secondary windings provide outputs to measuring instruments or protective relays. They also provide isolation from the high-voltage system for the purpose of safety.
What condition the relays should be use in power voltage?
Inorder to achieve the impedance maching ....
What are the three kinds of switching mechanism used in low voltage?
Transistors, relays, and triacs.
What makes relays click repeatedly when engine is trying to start but will not?
Low voltage, either caused by low system voltage, or faulty wiring or connection.
What are the advantages of instrument transformer?
'Instrument transformer' is the collective name for current transformers (CTs) and voltage (or 'potential') transformers (VTs/PTs). These transformers have two functions:to reduce the current or voltage in a high-voltage primary circuit to values that may be measured using regular ammeters or voltmeters ('burdens'), or to provide the current or voltage inputs to protection relays.to electrically-isolate their secondary burdens from the high-voltage primary circuit for the purpose of safety.
Why Normal time-overcurrent relays are not adequate for generator backup protection?
Setting the time-overcurrent relays high enough to prevent tripping for normal overloads may result in them not tripping at all due to the decaying characteristic of the generator fault current. Using the system voltage to control the overcurrent characteristic resolves this problem, since the voltage should drop very little for overloads, but will collapse to a small value for external faults. The 51V protection function uses the system voltage to adapt the operation of a time overcurrent element, using either voltage-restraint (51VR) or voltage-control (51VC).
