Complete Guide to Choosing the Right ATS Class

You have a big choice to make when picking between PC and CB class Automatic Transfer Switch Classes for your building. PC class switches use contactors to switch power quickly, but they need protection from other equipment. CB class switches use circuit breakers and have their own fault protection. What you pick will change how safe, legal, and reliable your system is. You want to choose the best one for your power system and not make expensive errors.

Key Takeaways

• Pick PC class or CB class Automatic Transfer Switches for your building. PC class works fast but needs extra safety parts. CB class has safety built in.
• Think about where you will put the switch. Make sure there is good airflow. This keeps the switch safe and working well.
• Follow local electrical rules like UL 1008 or IEC 60947-6-1. These rules help keep your power system safe and reliable.
• Test your Automatic Transfer Switch often to make sure it works. This helps protect your equipment and data during power loss.
• Choose a switch that can handle more load if your building gets bigger. This helps you avoid spending more money later.

Selecting Automatic Transfer Switch Classes

Quick Selection Overview

You have a big choice between PC class and CB class Automatic Transfer Switch Classes. The main difference is how each switch works and protects your electrical system. PC class switches use a contactor to move power fast. They need other devices to protect against faults. CB class switches use a circuit breaker. They have built-in fault protection and can handle bigger loads.

Tip: Always look at what your building needs before picking a switch. The right switch keeps your power system safe and working well.

Here is a table that shows the main things you should think about:

PC vs CB Class Differences

It is important to know how PC class and CB class Automatic Transfer Switch Classes work. PC class switches use an electromagnetic coil drive. This moves power quickly and fits in small spaces. These switches work well for network-to-network or network-to-generator setups. They usually support smaller loads. You control them with smart controllers that let you talk to them from far away.

CB class switches use a circuit breaker. This design is bigger and moves power more slowly. These switches are good for emergency systems and important jobs. They can handle bigger loads and let you control them by hand or automatically. CB class switches have fault protection built in.

Here is a table that compares the main features:

Step-by-Step Process

You can use a simple process to pick the right Automatic Transfer Switch Classes for your building. This helps you find the best switch for your needs.

1. Identify Load Types: Check if your loads are resistive or inductive. This helps you know which switch is better.
2. Check Electrical Current: Make sure the switch can handle the highest current in your system.
3. Match Voltage: The switch must work with the voltage of your generator and main power.
4. Consider Power Measurement: For big setups, pick switches that can measure power.
5. Select the Right Switch: Make sure the switch can handle your building’s load, current, and voltage.
6. Choose Installation Location: Put the switch near the main panel or generator. Make sure there is good airflow and clear labels.
7. Shut Off Power: Always turn off all power before you install the switch.
8. Follow Installation Protocols: Follow local rules and the maker’s instructions when you install.

Note: If you do these steps, your power system will be safer and work better.

Now you have a clear answer to your selection question, a simple comparison of PC and CB class switches, and easy steps to help you pick the right Automatic Transfer Switch Classes for your needs.

ATS Function and Importance

Power Continuity Role

Your building needs electricity to work safely. Automatic Transfer Switch Classes help keep the power on. They switch to backup power if the main source fails. Some switches move power faster than others. The table below shows how each switch helps keep power steady in important places:

Picking the right switch stops power cuts. This keeps equipment and data safe.

Operation Sequence

An automatic transfer switch works in steps when power goes out. First, it watches the utility power all the time. If there is a blackout or voltage drop, it finds the problem. The switch tells the backup generator to start. It waits for the generator to make steady power. Then, it moves the building’s load to the generator. The switch keeps checking if the utility power returns. When the utility power is stable, it moves the load back. The generator runs a few minutes to cool down. The switch turns off the generator and goes back to watching the power.

This process keeps your building powered without waiting.

Critical Applications

Automatic transfer switches are used in many important places. These switches protect people and machines where power loss is not allowed:

1. Healthcare: Hospitals need power for life-saving machines.
2. Data Centers: They must stop data loss and downtime.
3. Manufacturing: Factories need power to keep working.
4. Public Safety and Emergency Services: Police, fire, and rescue teams need power to respond fast.

Choosing the right Automatic Transfer Switch Classes helps these services stay safe and work well.

ATS Standards Overview

UL 1008 Compliance

You should know about UL 1008 when picking Automatic Transfer Switch Classes. UL 1008 is a safety rule for transfer switches in North America. This rule makes sure your switch works well in emergencies. It checks how fast the switch moves power, how strong it is, and if it stays safe when stressed.

Here is a table that shows the main things needed for UL 1008:

Tip: If you choose a switch with UL 1008, you help keep your building safe and follow code rules.

IEC 60947-6-1 Classification

You might see IEC 60947-6-1 if you work outside North America. This rule comes from the International Electrotechnical Commission. It covers transfer switches used in many countries. IEC 60947-6-1 checks how well the switch works, how safe it is, and how it handles problems. You should look for this mark if your project needs approval in other countries.

Standards in Selection

You should always check the rules before picking a switch. Rules help you find the right switch for your building. They also make sure your system is safe and legal. The table below shows how rules help you choose:

Remember, following rules helps you avoid trouble and keeps your power system working well.

PC Class ATS Features

Contactor Mechanism

You will find that PC class ATS uses a contactor mechanism. This means the switch uses an electromagnetic coil to open or close the circuit. The contactor moves quickly and does not take up much space. You can fit these switches in smaller panels. The simple design helps you get fast and reliable switching between power sources.

Upstream Protection

PC class ATS does not break short-circuit currents by itself. You must use upstream protection to keep your system safe. Here is how upstream protection works:

• PC class ATS cannot stop short-circuit faults.
• You need to install a circuit breaker or fuse before the ATS.
• The upstream device will trip if a fault happens, protecting your equipment.
• Switch-based ATS, like the DLQ3G series, use load-break switches and depend on upstream circuit breakers for safety.

Note: Always check that your upstream protection matches the ATS rating.

Fast Transfer Performance

You get very fast transfer times with PC class ATS. This helps keep your equipment running during power loss. The table below shows how PC class compares to CB class ATS:

A fast transfer time means your lights and machines stay on with little interruption.

Typical Uses

You will see PC class ATS in many commercial and industrial buildings. These switches help you move power from the main source to a backup without needing someone on site. You can set up the switch to follow a sequence, so only the most important loads get power during an outage. This setup reduces mistakes and keeps your system efficient. You can also connect the ATS to a load management system to control which loads turn on or off.

Ratings and Cost

PC class ATS supports a wide range of rated currents, from 63A to 630A. You can use them with AC 400V systems. The transfer time usually falls between 300 and 500 milliseconds. The table below compares ratings and cost with CB class ATS:

You can choose from 2P, 3P, or 4P configurations to match your needs.

When to Choose PC Class

You should pick PC class ATS when you need fast switching and have upstream protection in place. These switches work well in places where space is limited and transfer speed matters. You can use them in offices, small factories, and places with moderate power needs. If you want a cost-effective solution and already have good circuit breakers, PC class ATS is a smart choice for Automatic Transfer Switch Classes.

CB Class ATS Features

Breaker Mechanism

CB class ATS uses a breaker mechanism with good safety features. The breaker can handle short-circuit currents by making, carrying, and breaking them. The design is modular, so you can change parts easily if needed. A gear drive keeps both breakers from closing at the same time, which helps keep your system safe. The table below lists the main features:

Integrated Protection

CB class ATS has built-in protection. You do not need extra devices to keep things safe. The switch protects against over-voltage, reverse power, ground faults, and overloads. This makes your system simpler, with fewer parts and better reliability. Here is a table that explains these features:

Fault Handling

CB class ATS can handle electrical faults fast. The switch uses two circuit breakers to stop faults at the ATS. You do not need to use other protectors before the switch. This design makes your system more reliable and keeps it working. PC class ATS switches fast but cannot stop faults. CB class ATS can switch and protect, so it clears short-circuits by itself.

Common Applications

CB class ATS is used where power must stay on. These switches are good for industrial projects with strict rules about outages. Civil construction projects use them when they need reliable power. The table below shows where you might use them:

Ratings and Cost

CB class ATS can handle currents from 20A to 1600A. You can use them with AC 400V systems. The price starts at about $1,089.30 if you buy many at once. You get strong fault protection and high reliability, so they are a good choice for important places.

When to Choose CB Class

Pick CB class ATS if you need built-in protection and fault handling. These switches are best where safety and reliability matter most. You can use them in hospitals, data centers, and big factories. If your project needs Automatic Transfer Switch Classes that protect against faults and make your system simple, CB class ATS is the right choice.

Comparing Automatic Transfer Switch Classes

Mechanism and Construction

You will notice big differences in how PC class and CB class switches work inside. PC class switches use a contactor. This part moves fast and takes up less space. You can fit it into smaller panels. The contactor uses an electromagnetic coil to open and close the circuit. This design gives you quick switching and a simple build.

CB class switches use a circuit breaker. The breaker is bigger and heavier. It has more moving parts. You get a strong frame that can handle high fault currents. The breaker also has a gear system. This system stops both breakers from closing at the same time. You get a safer and more reliable switch, but it needs more room.

Tip: If you have limited space, PC class switches fit better. If you need a strong and safe build, CB class switches work best.

Protection Differences

You must think about protection when you choose a switch. PC class switches do not stop short-circuit faults by themselves. You need to add a circuit breaker or fuse before the switch. This extra device will trip if a fault happens. Your system stays safe, but you must plan for this extra part.

CB class switches give you built-in protection. The breaker can stop short-circuit currents right at the switch. You do not need extra devices. The switch also protects against overcurrent, ground faults, and reverse power. You get a simple system with fewer parts to worry about.

Performance Comparison

You want your power to switch fast and stay steady. PC class switches give you very quick transfer times. You can see transfer in less than 150 milliseconds. This speed keeps your lights and machines running with almost no pause. You get the best results in places where even a short power loss is a problem.

CB class switches take longer to transfer. The breaker needs more time to move. You may see transfer times over 1.5 seconds. This delay can affect sensitive equipment. But you get strong protection and can handle bigger loads. You must decide if speed or protection matters more for your building.

• PC Class: Fast transfer, best for sensitive loads.
• CB Class: Slower transfer, best for high protection and large loads.

Installation and Cost

You will find that PC class switches are easier to install. The small size lets you fit them in tight spaces. You spend less time and money on installation. The cost is lower, but you must buy extra protection devices.

CB class switches need more space. The installation takes longer because the breaker is bigger. You pay more for the switch, but you do not need extra protection parts. The total cost can be higher, but you get a safer and simpler system.

Note: Always check your budget and space before you choose. Think about the long-term cost, not just the price of the switch.

You can now see how the two main Automatic Transfer Switch Classes compare in every important way. This helps you make the best choice for your building.

Application Guidance by Facility Type

Data Centers

Your data center must always stay on. IT equipment is very sensitive and cannot have long power outages. You need switches that move power very fast, usually in 0 to 10 milliseconds. Static Transfer Switches (STS) are good because they switch quickly and protect servers from voltage problems. Pick a switch that works for your needs now and in the future. Make sure the switch can handle the fault current at your site or more.

Tip: Use ATS in 2N, N+1, or catcher systems to meet Tier III or IV needs.

Here is a table to help you remember what is important:

Always follow IEC 60947-6-1 and UL 1008 rules for safety and good work.

Hospitals

Hospitals need power for machines that save lives. You must use the right Automatic Transfer Switch Classes for each part of the emergency system. Level 1 systems protect people and need the fastest and most reliable switches. Use different switches for each part of the emergency system. Open-transition switches are okay if a short power break is fine. Closed-transition switches are best if you cannot lose power at all.

• Level 1: Use for life support and important care.
• Level 2: Use for less important things.
• Always follow rules for how fast switches must work.

Note: Test your switches often so they work when you need them.

Commercial Buildings

You want offices, schools, and stores to be safe and comfortable. Most commercial buildings can use PC class switches if you have good upstream protection. These switches fit in small places and switch power fast. For bigger buildings or important equipment, you may need CB class switches for more protection.

• Pick switches based on how big and important the load is.
• Put switches close to main panels for easy use.
• Label all switches clearly to keep people safe.

Industrial Facilities

Factories and plants need strong and steady power. You should use CB class switches for high fault currents and big loads. These switches have built-in protection and work well in tough places. Always check the fault current at your site and pick a switch that matches or is higher.

• Use modular switches so you can fix them easily.
• Test switches when you plan shutdowns.
• Write down all tests and repairs.

Now you can pick the right switch for your building and keep your power safe.

Practical Selection Guide

Location and Protection

You need to think about where you will put your automatic transfer switch. Place the switch close to your main power panel or generator. This helps you keep wiring short and safe. Make sure the area stays dry and cool. Good airflow keeps the switch from overheating. You should also check if the spot has enough space for the switch you choose. If you pick a PC class switch, you must add a circuit breaker or fuse before it. This extra device will protect your system from faults.

Tip: Always label your switches and protection devices clearly. This helps you and others stay safe during maintenance.

Code Review

You must follow local and national electrical codes. These rules keep your building safe and legal. Check if your area uses UL 1008 or IEC 60947-6-1 standards. Read the code requirements for transfer time, testing, and installation. If you do not follow the rules, you may face fines or delays. You can ask a licensed electrician or inspector for help.

Fault Coordination

You need to make sure your system can handle faults. If you use a PC class switch, add an upstream breaker that matches the switch rating. For CB class switches, you get built-in fault protection. Always check the fault current at your site. Pick a switch that can handle more than the highest fault current you expect.

Speed and Load Type

Think about how fast you need the switch to work. Data centers and hospitals need very fast transfer times. Offices and stores can use slower switches. Check if your loads are sensitive, like computers or medical devices. Sensitive loads need fast and smooth switching.

• Fast transfer: Use PC class or static switches.
• High protection: Use CB class switches.

Cost and Design

You must balance your budget with your needs. PC class switches cost less but need extra protection devices. CB class switches cost more but include protection. Look at the total cost, not just the price of the switch. Choose a design that fits your space and keeps your system simple.

Note: Plan for future growth. Pick a switch that can handle more load if your building expands.

Risks of Misapplication

Safety and Reliability

You must choose the right automatic transfer switch class for your building. If you pick the wrong one, you put people and equipment at risk. A misapplied switch can fail during a power outage. This failure can cause fires, electric shocks, or damage to machines. You may lose important data or stop life-saving equipment.

Here are some risks you face if you use the wrong ATS class:

• Fire Hazard: If you use a PC class switch without proper upstream protection, it cannot stop short-circuit currents. This can lead to overheating and fire.
• Equipment Damage: Sensitive devices can break if the switch does not transfer power fast enough or cannot handle faults.
• Power Loss: A slow or faulty switch can cause long outages. This can stop work in hospitals, data centers, or factories.
• Injury: People can get hurt if the switch does not protect against electrical faults.

⚠️ Tip: Always match the ATS class to your load type and protection needs. Test your system often to catch problems early.

Avoiding Code Issues

You must follow electrical codes when you install an ATS. If you do not, you can face fines or have to redo your work. Codes like UL 1008 and IEC 60947-6-1 set rules for safety and performance. Inspectors check if your system meets these rules.

Here is a table to help you avoid code problems:

✅ Note: Read your local codes before you buy or install an ATS. Ask an expert if you are not sure.

You keep your building safe and legal when you choose the right ATS class and follow all rules.

You now understand how PC and CB class ATS differ in switching speed, protection, and installation. PC class ATS gives you fast transfer but needs extra protection. CB class ATS offers built-in safety for bigger loads. Always check standards like UL 1008 or IEC 60947-6-1 before you choose.

• Review your building’s needs.
• Use the step-by-step guide.
• Ask an expert if you feel unsure.

Choosing the right ATS keeps your power system safe and reliable.

FAQ

What is the main difference between PC class and CB class ATS?

You will see that PC class ATS uses a contactor for fast switching. CB class ATS uses a circuit breaker for built-in protection. PC class needs extra protection devices. CB class handles faults by itself.

Can I use a PC class ATS without an upstream breaker?

No, you must use an upstream breaker or fuse with a PC class ATS. This device protects your system from short-circuit faults. Without it, your equipment can get damaged.

Which ATS class should I use for a hospital?

You should use CB class ATS for hospitals. This class gives you built-in protection and handles large loads. It keeps life-saving equipment safe and running during power loss.

How do I know if my ATS meets code requirements?

Check the label on your ATS. Look for UL 1008 or IEC 60947-6-1 marks. These show your switch meets safety and performance rules. You can also ask an electrician for help.

See also

What Sets a Low-Voltage Box Apart from Regular Electrical Boxes

Automatic transfer switch

How to use ATS in conjunction with a generator

What to Know Before You Purchase an Automatic Transfer Switch

What Is the Full Name of ATS in Electrical Systems