Split Core CTs and Why Size Matters
Current transducers (CTs) are a critical component of power monitoring. They come in a variety of formats, sizes, current ratings and accuracy levels. The aspect we would like to focus on here is size, specifically inside diameter.  

The inside diameter (ID) is the width of the opening in the CT that the conductor goes through. It must be large enough to fit around the conductor, however choosing too large of a CT can create other issues. As the graphic above indicates, the overall dimensions of the CT grow substantially as the ID gets bigger. 

Current Rating
Be sure to use a CT with a current rating as close to the actual current being monitored as possible to maximize accuracy at the lowest possible load. A CT will be accurate across some portion of its range. For example, a 200 amp CT that is +/- 1% accurate might maintain that accuracy from 5% to 120% of its rated capacity (i.e. on loads between 10 and 240 amps). 

Inside diameter
CTs of the same amperage come in different sizes. For example, Packet Power offers 200 amp CTs with 24mm, 36mm and 50mm IDs. The chart below shows that a 200A CT with a 50mm ID is much larger than one with a 24mm ID. Since space inside electrical equipment is often tight, using a CT that is larger than needed can create problems as well. 
CT sizing summary
Most customers will try to match the amperage of the CT to the rating of the over-current protection on the circuit. You need to know both the circumference of the conductor(s) that the CT has to fit around (to determine the minimum acceptable ID) and the amount of available space in the panel where the CTs will be installed. If the conductor is very large or the space is particularly tight, a Rogowski coil ("rope CT") might be the best choice.  

Packet Power offers multi-circuit monitoring and branch circuit monitoring solutions that are custom-built to customer specifications. We've developed a configuration checklist to help customers create the ideal solution for their needs including the best split core CT.

For a good overview of split core vs. solid core CTs reference "Split core, Solid Core, and Why you Should Care". 
Vertiv Geist Environmental Monitors
One option to monitor a network closet is wired sensors. This involves a head-end unit with multiple sensors connected to it that is then connected to the network. You would typically have temperature and humidity at minimum with optional additional sensors such as leak and contact closure. The head-end unit has its own management interface or, if there are multiple closets, it is preferable to have a management interface that connects to all the head-end units. 

Whether your Data Center is Managed On-Premise,
Co-located Off-Site, or Sitting on the Edge...It Needs:
As a Data Center Operator, your list of concerns seems to get larger every day. From operations to budget management, from corporate compliance to aging equipment, and lest we not forget COVID-related issues… the health of your Critical Infrastructure should be the least of your concerns.

Through our Power Health Assessment, our Team works with you to assure you understand the current state of your network health, and (if needed) can help you develop a plan to address those weak links needing to be strengthened.
We’ll partner with you to analyze:
  • UPS performance to load capacity across facilities
  • “Hot Aisle” vs. “Cold Aisle” and managing unusual IT airflow patterns
  • Performance compared to ASHRAE recommendations
  • Foundational role of rack expansion planning
The Readers Corner
Bring Air in at the Top of the Rack
Did you know when the intake temperature is above the optimal range, your network gear can experience a 54% higher failure rate? Vertiv Geist SwitchAir provides a path for cool air to travel to the intake of top-of-rack network switches in a typical hot aisle/ cold aisle data center design. SwitchAir lets you take control of your critical network equipment to improve the life expectancy and reduce the chance of premature failure ultimately resulting in costly unplanned downtime.
Access, Inc. is Wisconsin, Michigan, and NW Ohio's premier source of Heating, Ventilating and Air Conditioning (HVAC) and critical support equipment and services.

We work hand in hand with business owners, contractors, value added resellers, and engineers, helping them apply our products and services to solve their HVAC and critical support problems in the most reliable and economic way.
Our Mission:
Ensuring uptime with market-leading, reliable and
performance-driven solutions.
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