Home » Blog » Experience » Current transformer selection

# Current transformer selection

When you want to select current transformer with appropriate rated power for your power system, you need to consider that value of rated power of selected current transformer should be higher from sum of values of load and Joules' losses which are a consequence of flow current through conductors which connect current transformer with relay.

So, if you have a long distance between current transformer and relay, then you need to consider one of two following manners for solving this problem:

1. replacing existing current transformer with current transformer with higher power,

2. replacing existing conductors with conductors with lower cross-section.

This solution is a consequence of necessity for reducing of Joules' losses which are a consequence of flow current through conductors which connect current transformer with relay. If you have conductors whose value of rated current is 5A, you will have Joules' losses P=R*I^2=R*5^2=25*R. Otherwise, if you have conductors whose value of rated current is 1A, you will have Joules' losses P=R*I^2=R*1^2=R.

On this way, Joules' losses in your selected conductors will be reduced 25 times and selected current transformer will be unloaded by reducing additional load.

So, if you have a long distance between current transformer and relay, then you need to consider one of two following manners for solving this problem:

1. replacing existing current transformer with current transformer with higher power,

2. replacing existing conductors with conductors with lower cross-section.

This solution is a consequence of necessity for reducing of Joules' losses which are a consequence of flow current through conductors which connect current transformer with relay. If you have conductors whose value of rated current is 5A, you will have Joules' losses P=R*I^2=R*5^2=25*R. Otherwise, if you have conductors whose value of rated current is 1A, you will have Joules' losses P=R*I^2=R*1^2=R.

On this way, Joules' losses in your selected conductors will be reduced 25 times and selected current transformer will be unloaded by reducing additional load.

For AM & FM radio & some data communications adding the QP filter make sense.
Now that broadband, wifi, data communications of all sizes & flavours exist - any peak noise is very likely to cause ...

At zero speed the motor requires torque which is flux (voltage) and current (mostly reactive). Only a little bit of active current to compensate for the motor power losses.
Only the power losses need to be ...

Where we really need digital communication networking, in my personal opinion, is down at the sensor/transmitter and positioner/actuator/valve level to take the place of 4-20 mA and on/off signals. Down at the ...

1. How does this affect the vector group (YNd1) of the transformer? Will it be changed to YNd11?
2. Will it make any difference as far as the vector group is concerned if instead of phase A and C, phase B ...

You can calculate current setting of overcurrent relay by using next expression:
Isetting ≥ (ks*Imaxopam)/(a*pi)
Imaxopam=kam*Imaxoptr

Gozuk Blog: all about electric motor control & drives industries development in energy saving applications.

Like pumps, fans consume significant electrical energy while serving several applications. In many plants, the VFDs (variable ...
A frequency inverter controls AC motor speed. The frequency inverter converts the fixed supply frequency (60 Hz) to a ...
Motor starter (also known as soft starter, motor soft starter) is a electronic device integrates soft start, soft stop, ...
Soft starter allows the output voltage decreases gradually to achieve soft stop, in order to protect the equipment. Such as the ...
Soft Starter reduces electric motor starting current to 2-4 times during motor start up, reduces the impact to power grid during ...

Servo system

High Efficiency Converters - Next Generation

Can anybody tell me the difference between DCS and PLC's?

WHAT REAL TIME MOTION CONTROL SYSTEM DO YOU USE?

What is relation between frequency and voltage?

How to connect CU320-2 PN in Tia Portal V11 SP2.

Active PFC Topology - 115 Vac, 60 Hz input to 90 VDC at 6 Amps (540 Watts) output?

How do you think of PV Power Optimizer?

High Efficiency Converters - Next Generation

Can anybody tell me the difference between DCS and PLC's?

WHAT REAL TIME MOTION CONTROL SYSTEM DO YOU USE?

What is relation between frequency and voltage?

How to connect CU320-2 PN in Tia Portal V11 SP2.

Active PFC Topology - 115 Vac, 60 Hz input to 90 VDC at 6 Amps (540 Watts) output?

How do you think of PV Power Optimizer?