CT ( Current Transformer ) Meters are installed on any connections with a load greater than 100 Amps. ... A CT meter only measures a fraction of the current passing through the connection and a multiplier is applied to this reading to reflect the actual current.
How does CT meter work?
A CT rated meter socket carries an induced current , reducing the amperage of the current running through the meter. This is done through the use of current transformers, or CTs, which measure alternating current and produce a secondary current in phase with its primary current in a predetermined ratio.
What is a CT meter used for?
A CT meter is a device that measures amperage in one or more conductors using sensors called current transformers (CTs). Current transformers come in many sizes and amperage ratings which allows a single meter to measure all kinds of electrical loads.
What is CT in electricity?
A Current Transformer (CT) is used to measure the current of another circuit. ... In doing so, the current transformer reduces a high voltage current to a lower value and therefore provides a safe way of monitoring electrical current flowing in an AC transmission line.
What is CT connection?
CT (Current Transformer) Meters are installed on any connections with a load greater than 100 Amps. Conventional meters cannot be used to measure current for these larger connections as they would simply have to be too large to be practicable.
Why CT is required?
Why it’s done
Your doctor may recommend a CT scan to help: Diagnose muscle and bone disorders , such as bone tumors and fractures. Pinpoint the location of a tumor, infection or blood clot. Guide procedures such as surgery, biopsy and radiation therapy.
How do I choose a meter for CT?
For a metering CT, choose a burden VA equal to, or greater than, 125 % of the total combined VA of instruments connected to the secondary side . For a protective CT, please contact the manufacturer for assistance. Accuracy • For a revenue CT, the accuracy should be at least IEC 0.2 or 0.5 CL or IEEE 0.3 or 0.6 CL.
How is CT meter reading calculated?
When analog ammeters are installed, we can easily determine the CT ratio by observing the meter full scale value and then divide that value by 5 . Figure 3. Ammeter with a full scale of 150 amps.
How is CT ratio calculated?
Definition: 1) The ratio of primary amps divided by secondary amps . 2) The current ratio provided by the windings of the CT. For example, a CT that is rated to carry 200 Amps in the primary and 5 Amps in the secondary, would have a CT ratio of 200 to 5 or 40:1.
What happens when you open circuit a CT?
Open circuit condition in a current transformer (CT) can result in dangerous over voltage condition at the secondary terminals of the CT . An open circuit CT especially of high ratio and carrying high currents can produce secondary open circuit voltage in the range of few kilo volts.
What is burden of CT?
The burden is the termination impedance of the measuring instrument . The measuring instrument can be an analog or digital energy meter, a data logger or a recorder. ... Technically, the total burden for a CT is the internal winding resistance, the connecting lead resistance and the measuring instrument input resistance.
Do I need a CT meter?
Current Transformer (CT) Metering is a requirement for supplies with an anticipated load of over 100Amp/ 70kVA. Anyone installing or refurbishing power supplies rated >100Amp/ 70kVA will need to incorporate CT metering in their design.
How do I connect to CT?
- Install CTs on the phase conductor that corresponds to the voltage input phase.
- Install CTs with the arrow or label ‘This side toward source’ facing towards the breaker feeding the load.
- Connect the white and black CT leads to the corresponding CT input terminals with the white and black dots.
How do you test for CT?
A CT ratio test can be performed by injecting a primary current and measuring the current output , or by injecting a secondary voltage and measuring the induced primary voltage.
What happens if CT polarity is reversed?
Generally current transformer is called as CT. ... Otherwise (polarity reversed), the devices starts malfunctioning , i.e energy meter shows negative readings, relay may read negative current hence relay may activate the trip circuit, reverse power relay activation is alternator or generator circuits etc.
What is a drawback to using a CT scan?
In general, a CT scan has the advantage of short study time (15 to 20 minutes) with high quality images. However, disadvantages include the need for ra- diation exposure and the use of a contrast material (dye) in most cases , which may make it inappropriate for patients with significant kidney problems.
