HEYI CCT-24 (clamp on current transformer) 

What are the uses, advantages and disadvantages of CCT-24 ?

HEYI Electric’s CCT-24 is a clamp on current transformer designed for quick installation and can adapt well to use in narrow spaces. The product can be produced with an internal high-precision resistor to achieve output voltage, making it suitable for monitoring various currents and voltages to adapt to various alarm and collection scenarios.

Product Overview

The clamp-on design allows for direct attachment to conductors such as current rails and copper busbars without removing wires , facilitating installation , renovation, and maintenance of power projects . Its compact size makes it ideal for distribution cabinets or ring main boxes where space is limited .

If voltage output monitoring is required, during the production process of our products, an internal precision resistor is connected across the secondary circuit to directly provide a low safety voltage output (which is convenient for direct reading by certain voltage-type input monitoring devices).

Key parameters of the product:

Primary range: AC 0–250 A.

Secondary output:0–250 mA (note that this is the secondary caliber of current level), and 0.333 V, 0–1 V are also listed as output options/forms.

Accuracy 0.5 class, frequency 50/60Hz.

Installation without power outage:

No need to shut down the power or disconnect the line during on-site maintenance or renovation, which greatly improves production efficiency .

The small-sized clamp on current transformer is very suitable for power construction in narrow spaces such as distribution cabinets, ring network cabinets, door post cable passages, etc. It is faster to install than solid-core full-circle threading CT .

At the same time, according to user needs, we can build precision resistors into the product , so it can directly output low voltage and directly drive voltage -type acquisition modules or alarms , eliminating the trouble of external shunts / load resistors ( we can also design different current outputs according to different terminal devices ).

What are the typical application scenarios of Heyi’s CCT ?

1.Current monitoring and early warning in distribution cabinet/ring main cabinet ;

2.Fault indicator/overcurrent monitoring of underground cables or overhead lines;

Cooperate with energy collection equipment, remote monitoring unit (RTU/PLC), and ring main unit monitoring system to provide online monitoring and alarm.

How to select products and conduct on-site wiring?

1.The first step is to determine the primary current input size : select a model based on the maximum continuous current of the circuit (0–250 A) to avoid circuit saturation caused by too low a rated current .

2.Next, confirm the output type of the secondary interface : three common options are “0–250 mA , ” “0.333V , ” and ” 0–1V . “

First, confirm whether the target acquisition device reads current signals (mA) or voltage signals (V), as the wiring methods for the two are different .

For example, if the secondary output is 250 mA and 0.333 V appears across the internal resistor, then the resistor value is approximately 0.333 ÷ 0.25 = 1.332 Ω .

Match the correct load (burden):

Although the CCT has a precision resistor internally , the input impedance/range of the connected ammeter must be confirmed to avoid reading deviation or exceeding the allowable error due to impedance mismatch.

Installation environment/protection requirements :

If used outdoors or in humid environments (such as underground cable wells), you need to confirm whether to select a waterproof housing or additional protective parts (the CCT series has outdoor waterproof models such as OCT-36 mentioned in the information; different models have different focuses).

Installation and safety precautions :

Note : The secondary circuit of the current transformer must not be open-circuited. If the secondary circuit is open , a very high voltage will be generated , which will pose a great safety hazard .

During construction, the secondary side may need to be short-circuited or connected to a suitable load .

The current conductor ( such as cable, busbar ) should be clamped in the middle of the transformer window as much as possible to avoid deviation affecting the monitoring accuracy .

Tighten the fixing screws/terminals into place without damaging the housing or terminals.

After wiring is complete, perform a calibration of the 1% to 120% range : you can first use a known current source or a temporary load to check whether the output is within the tolerance range.

If the device is sensitive to temperature drift or requires high-precision measurement (measurement level rather than just monitoring), it is recommended to give priority to solid single- perforation measurement CT or choose high-precision products; clamp-on type is more suitable for monitoring and alarm scenarios.

How to choose an alternative if the split-core transformer encounters limitations?

1.Compared with solid core current transformers, clamp-on current transformers are more accurate, especially when long-term high-precision current measurement is required ;

however, their convenience in maintenance and modification scenarios is irreplaceable .

2.Some circuit monitoring systems only monitor standard secondary currents of 0–5 A or 0–1 A.

If voltage-output CTs are used , external adapters or adjustments to the selection are required .

peak current or current waveform distortion is severe (such as high-power motor starting or heavy harmonics), the current saturation current frequency response should be evaluated.

the clamp-on CT is that it can be installed without turning off the power, which saves time at the renovation site.

It can also directly output low voltage to the monitoring device, making on-site wiring simpler.”

“The CCT-24 offers a primary range of 0–250A, and internal precision resistors support 0.333V/0–1V output options, making it suitable for online monitoring of ring main units and underground cables.

(However, if metrological-grade accuracy is required, it is recommended to evaluate a solid-state through-hole CT.)”

Summarize

The CCT-24, a small clamp on current transformer, is a very practical tool in retrofit, monitoring, and alarm applications: it installs quickly, takes up little space, and its output is easily connected to monitoring equipment.

However, for high-precision measurement or extreme operating conditions, careful consideration must be given to the selection of a through-hole/metering-grade CT.

Compay：HEYI Electrical Co., Ltd.

Brand: HEYI/ASCT

Contact: Bethy

E-mail: heyi@heyiele.com             

Tel: 86-13968747975

 

 

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