use of CT
When the secondary of a transformer is opened, there is no longer any load on the transformer. There will be some current flowing in the primary winding, which is needed to induce the voltage in the secondary. This primary current is referred to as the "no load" current, and is indicative of the core losses in the transformer.
Substation main components include the following:1. The power transformer which is the heart of the Substation. It is the Power transformer that steps up (in the case of a step up Substation for transmission) or steps down (in the case of step down Substation for distribution) the voltage e.g. 132/33kV (step down), 33/132kV (step up).2. The Auxiliary transformer (which is fed from the output of the Power Transformer). This transformer powers the substation accessories and auxiliary equipments such as controls, lighting, Substation control room etc)3. Disconnecting switch or Isolators4. Earthing switch for grounding the main line in case there is need for maintenance work5. Control relays and Protective relays for short circuit, over voltages etc6. Instrument transformers e.g. voltage transformers, current transformers that will take current from the main high voltage line in case of an over current on the line and produce a current that the protective relays can operate with.7. Supervisory Control and Data Acquisition (SCADA) systems for line monitoring and control8. DC power supply system in the form of batteries for supplying DC loads such as emergency lightings, relays, rectifiers, chargers etc.9. Lightning arrestors10. Surge arrestors11. Switchgears for the high and low voltage levels, AC/DC panels12. Circuit breakers for the high and low voltage levels
A current transformer works on the same principle as that of a simple transformer however it steps down the high current into a low level so that it can be measured using an ammeter of a suitable range. In some current transformers extra cores are provided. This is done in order to prevent the faulty currents i.e. the over currents, earth faults, differential protections. The extra cores of a C.T. gets saturated as soon as the faulty currents starts flowing and thereby does not harm the main core of the transformer and the ammeter connected. The C.T. is always connected in the line carrying current. It first steps down the current to a measureable form and further gives this current to the ammeter.
Almost all of the equipment inside of a substation is used for the purpose of protection. The circuit breakers and power transformers in the substation are equipped with current transformers (CTs) that step down the current passing through the equipment to a level that can be read by protective relays. These protective relays can cause the breakers to trip upon many different events including under/overvoltage, current spikes, frequency issues, transformer/bus differential, etc. The breakers in a substation are placed strategically so that different pieces of equipment or sections of a circuit can be isolated without loss of service to the customer.
Yes, a transformer has eddy currents.
Current transformer and voltage transformer . This transformers are actually measuring instruments which measures the quantity of current and voltage coming out of the substation.
When the secondary of a transformer is opened, there is no longer any load on the transformer. There will be some current flowing in the primary winding, which is needed to induce the voltage in the secondary. This primary current is referred to as the "no load" current, and is indicative of the core losses in the transformer.
To calculate the no load current from transformer & core loss is also calculated.
Substation main components include the following:1. The power transformer which is the heart of the Substation. It is the Power transformer that steps up (in the case of a step up Substation for transmission) or steps down (in the case of step down Substation for distribution) the voltage e.g. 132/33kV (step down), 33/132kV (step up).2. The Auxiliary transformer (which is fed from the output of the Power Transformer). This transformer powers the substation accessories and auxiliary equipments such as controls, lighting, Substation control room etc)3. Disconnecting switch or Isolators4. Earthing switch for grounding the main line in case there is need for maintenance work5. Control relays and Protective relays for short circuit, over voltages etc6. Instrument transformers e.g. voltage transformers, current transformers that will take current from the main high voltage line in case of an over current on the line and produce a current that the protective relays can operate with.7. Supervisory Control and Data Acquisition (SCADA) systems for line monitoring and control8. DC power supply system in the form of batteries for supplying DC loads such as emergency lightings, relays, rectifiers, chargers etc.9. Lightning arrestors10. Surge arrestors11. Switchgears for the high and low voltage levels, AC/DC panels12. Circuit breakers for the high and low voltage levels
Batteries are essential components in a substation. They provide the (tripping) current by which protective relays can trip high-voltage circuit breakers in the event of a fault. This means that the circuit breakers can trip even if the substation itself has lost its ancillary AC power supply.
To limit the current flowing through the primary circuit.
a very helpful functionAnswerBatteries are essential components in a substation. They provide the (tripping) current by which protective relays can trip high-voltage circuit breakers in the event of a fault. This means that the circuit breakers can trip even if the substation itself has lost its ancillary AC power supply.
Current transformers are used to measure electric currents. When current in a circuit is too high to directly apply to measuring instruments, a current transformer produces a reduced current accurately proportional to the current in the circuit, which can be conveniently connected to measuring and recording instruments.
A current transformer works on the same principle as that of a simple transformer however it steps down the high current into a low level so that it can be measured using an ammeter of a suitable range. In some current transformers extra cores are provided. This is done in order to prevent the faulty currents i.e. the over currents, earth faults, differential protections. The extra cores of a C.T. gets saturated as soon as the faulty currents starts flowing and thereby does not harm the main core of the transformer and the ammeter connected. The C.T. is always connected in the line carrying current. It first steps down the current to a measureable form and further gives this current to the ammeter.
Transformers are not intended to be operated in DC. DC does not provide the continuously fluctuating current that a transformer requires in order to function. On DC, a transformer will act as a transient mode inductor, and settle out to a high current state, destroying itself.
The neutral wire is called a grounded conductor. It is also a current carrying conductor. It carries the unbalance current back to ground. At the substation the neutral is derived at the XO connection at the transformer. It needs to be grounded to earth. If not, you will have fluctuation of voltage on all phase wires to ground. With substations voltages being in access of 5kv in most cases. this fluctuation can be very vast.
in welding machine, the transformer used is basically a current transforrmer. so by changing the tap of secondary side of transformer, we can increase or decrease the current in the transformer.