You're probably aware that EMSCO is a top provider of used, reconditioned, and surplus industrial electrical equipment. However, you might not know that beyond just being the largest supplier, we also can tailor our products to your exact needs. Let's discuss one aspect of this customization: trip units, specifically the AC Pro and AC Pro II trip units.

EMSCO does more than supply individual replacement parts. This Square D I-Line distribution lineup is an example of the larger power distribution equipment our team can recondition, test, configure, and prepare for a customer's application.

For this project, EMSCO reconditioned a Square D I-Line distribution lineup for a customer in Kentucky. The equipment included main and distribution sections, multiple circuit breakers, and surge protection. The photos below show the equipment during the reconditioning process and after completion.

Project Configuration

The Square D I-Line lineup included:

• 2000A main breaker section with LSIG protection
• 1200A distribution breaker section with LSI protection
• Square D Surgelogic surge protective device
• Two 400A breakers
• Ten 200A breakers
• One 60A breaker

EMSCO stocks a broad range of Square D electrical equipment, including equipment for existing and legacy power distribution systems. Our online inventory represents only part of what we have available, so customers can also contact us when a specific configuration is not shown online.

During Reconditioning

The lineup was prepared and reconditioned in-house before final assembly and shipment.

Completed and Ready for Shipment

After reconditioning, the equipment was assembled and prepared for shipment to the customer.

More Than a Finished Appearance

Reconditioning is about more than making equipment look good. The used circuit breakers supplied with this lineup were load-tested, and test reports were provided with the equipment.

That is an important part of what EMSCO can provide. We maintain a large inventory of industrial electrical equipment and have the in-house capabilities to prepare equipment for real-world replacement, expansion, and power distribution projects.

In addition to complete lineups like this one, EMSCO stocks used and reconditioned switchgear and a large selection of used, tested, and reconditioned circuit breakers from Square D and other major manufacturers.

Need Square D I-Line Equipment?

Whether you are replacing existing equipment, adding distribution capacity, working with an older Square D I-Line system, or looking for equipment that is difficult to source new, EMSCO can help.

Send us the information you have—including manufacturer, amperage, voltage, catalog numbers, nameplate photos, breaker requirements, or project specifications. Our team can check available inventory and help identify equipment that matches your requirements.

Contact EMSCO for availability, project help, or a quote.

Westinghouse TAP, ITAP and ZTAP bus plugs can look very similar, but they are designed for different busway systems and are not interchangeable.

If you're trying to replace an existing Westinghouse or legacy Cutler-Hammer bus plug, don't identify it by enclosure shape alone. The part-number prefix, stab arrangement and hanger width can help determine which series you have.

TAP vs. ITAP vs. ZTAP: Quick Identification

The biggest trap is TAP vs. ZTAP. Both can have aligned stabs, and a ZTAP plug may even have a part number beginning with TAP. That's why the label alone isn't always enough.

How to Identify a TAP Bus Plug

TAP bus plugs are used with Westinghouse Standard-Design busway rated from 225A through 1000A. They were available in both 3-wire and 4-wire configurations.

The easiest clues to check are:

• Stabs: The phase stabs are aligned in a row.
• Neutral: On a 4-wire TAP plug, the neutral is offset from the phase stabs.
• Part number: The product label typically begins with the prefix TAP.
• Hanger width: TAP hanger brackets measure approximately 9-5/8 inches wide.

That last measurement becomes especially important when distinguishing a TAP plug from a ZTAP plug.

How to Identify an ITAP Bus Plug

ITAP bus plugs are used with Westinghouse Pow-R-Way I and Pow-R-Way II busway rated from 225A through 4000A. They were also available in 3-wire and 4-wire configurations.

ITAP is usually the easiest of the three families to identify:

• Stabs: ITAP stabs have a distinctive staggered or offset arrangement.
• Part number: The product label should use an ITAP prefix.

If the stabs are aligned rather than staggered, you're likely looking at a different Westinghouse bus plug family.

How to Identify a ZTAP Bus Plug

ZTAP bus plugs are used with Westinghouse Low-Impedance busway rated from 1000A through 4000A. ZTAP plugs can be more difficult to identify because of their similarity to TAP plugs.

Look for these clues:

• Stabs: The phase stabs are aligned.
• Neutral: On a 4-wire ZTAP plug, the neutral stab is also aligned with the other stabs.
• Hanger width: ZTAP hanger brackets measure approximately 11-5/8 inches wide.
• Part number: Don't rely on the prefix alone. ZTAP plugs may also have part numbers beginning with TAP.

The wider hanger brackets are one of the best physical clues. Compared with the 9-5/8-inch TAP hanger, the ZTAP hanger measures approximately 11-5/8 inches and extends farther beyond the enclosure.

TAP or ZTAP? Check These Two Details

If you're stuck between TAP and ZTAP, focus on hanger width and the neutral stab position.

Do not order a replacement based only on seeing "TAP" on the label. Check the physical configuration as well.

What to Send EMSCO for a Replacement Bus Plug

If you're still not sure which Westinghouse bus plug you have, don't guess. Send us enough information to verify the series before ordering.

For the fastest match, send:

• A clear photo of the bus plug nameplate
• A photo showing the stab configuration
• A photo of the busway nameplate, if available
• The hanger width if you're trying to distinguish TAP from ZTAP
• Amperage and voltage
• 3-wire or 4-wire configuration
• Ground requirements
• Breaker or fusible configuration

EMSCO stocks used, surplus, obsolete and professionally reconditioned bus plugs, including legacy Westinghouse and Cutler-Hammer equipment. Not everything in our inventory is listed online, so contact us if you don't see the exact plug you need.

Shop Bus Plugs   |   Busway & Plugs   |   Ask EMSCO for Help Identifying Your Bus Plug

The safety of any transformer or other electrical device should always come first. Low Voltage and Medium Voltage Encapsulated Dry Resin Transformers testing is required for safe operation. We can find any potential problems or weaknesses in the insulation of dry resin-filled transformers by performing routine testing. These tests allow us to take preventive action for your secure working environment.

Encapsulated Dry Transformer Components for Safety and the Environment

Electrical transformers that don't need a liquid coolant like oil are known as dry transformers. You may know them as resin-filled transformers, cast resin transformers or solid insulated transformers.

They use air for insulation and cooling. Dry transformers are popular because of their safety, effectiveness, and environmental friendliness in commercial and industrial environments. They are used in manufacturing facilities, renewable energy production, power distribution systems, and other areas.

Dry transformers are made up of a number of essential parts. The primary components consist of a laminated steel core that minimizes energy losses and a copper or aluminum conductor coil. Paper, fiberglass, or epoxy resin are used to insulate these windings, ensuring both electrical insulation and protection from impurities and moisture. For safety and cooling, the transformer is housed in a solid, vented casing.

Let's take a look at Megger test equipment for dry transformers and looking at the test results.

Megger Test Equipment Finds Insulation Weakness, Moisture, Safety Hazards

What is a megger test? Megger test equipment is effective for identifying moisture, insufficient insulation, and other possible problems in transformers. The test procedure includes applying DC voltage to the transformer windings during the test. The Megger test assists in locating any deterioration or breakdown in the insulation material by evaluating insulation resistance.

When looking at your megger test report, keep in mind the resistance reading will be lower than expected if the insulation is damaged, suggesting potential defects or moisture infiltration. With the help of this test, insulation issues like cracks, contaminants, or age can be found that could otherwise result in electrical problems, short circuits, or even catastrophic failures. Early detection of these problems allow necessary repairs or maintenance to be carried out, ensuring peak performance and averting safety risks. If you’re looking to invest in megger test set, check out the Megger Trax 220 Test Set for insulation resistance, winding resistance, turns ratio, dissipation factor, and more.

Transformer Megger Test Step-by-Step Procedures

Safety First:  Make sure the transformer is totally de-energized and you’re wearing appropriate personal protective equipment (PPE).

Setting up the Megger:  Prepare your Megger test device according to manufacturer directions. Verify that it’s calibrated and in good working order.

Disconnect Power:  To prevent incidents from occurring, make sure the transformer's power supply is completely cut off.

Clean your Transformers:  Clean the transformer's terminals and insulating surfaces. Any debris, moisture, or dirt that could compromise the test's accuracy should be removed.

Connect the Leads:  It’s recommended to connect the lead with the higher voltage (often red) to the high-voltage side and the lead with the lower voltage (typically black) to the low-voltage side.

Set Megger Test Duration:  The typical time frame is one minute, but it's always a good idea to check the manufacturer's instructions for any particular specifications.

Launch the Test:  Turn on the testing device. The transformer windings will receive a high-voltage DC voltage, and the instrument will measure the insulating resistance.

Interpret Megger Test Results: Compare insulation resistance with the reference value or the range the OEM specifies.

Based on test results, no urgent intervention may be needed if the insulating resistance is within the manufacturer’s stated range. Do repairs or arrange for maintenance if the reading falls below the designated threshold.

Looking for a Medium Voltage Dry-Type Transformer Testing Service?

This test helps you identify risks and prevent electrical faults or failures by identifying insulation weaknesses, moisture and other potential problems. The Megger test offers useful information about the insulation integrity of the transformer when you’re doing maintenance and repairs to maintain performance and avoid safety risks. Regular Megger testing extends the life and dependability of transformers in a safe environment. Make megger testing a routine and seek professional services if you’re not qualified to use the testing equipment.

Looking for a Medium or Low Voltage transformer or having one tested? A Megger Testing Service for transformers using test equipment like the Megger Trax 220 Test Set is crucial for verifying the effectiveness and safety of transformers.

Contact EMSCO customer service to arrange testing. Ask about EMSCO testing services for dry-type medium voltage transformers. Our new Megger Trax 220 Test Set allows us to perform a wide range of tests, including insulation resistance, winding resistance, turns ratio, dissipation factor, and many others.

In the realm of industrial power distribution, ensuring safety, reliability, and efficiency is of utmost importance. To protect electrical circuits and equipment from overcurrents and short circuits, engineers often turn to molded case circuit breakers (MCCBs). These robust and versatile devices play a crucial role in safeguarding industrial power systems, ensuring smooth operations and preventing potential hazards. In this blog post, we will delve into the features, benefits, and applications of molded case circuit breakers in industrial settings.

The Anatomy of Molded Case Circuit Breakers:
Molded case circuit breakers are named after their housing, which is typically made from molded insulating materials such as plastic or fiberglass. Inside the casing, these breakers comprise essential components like the trip unit, operating mechanism, and current-carrying contacts. The trip unit is responsible for detecting overcurrent conditions and tripping the breaker when necessary, while the operating mechanism ensures the mechanical action of opening and closing the circuit.

Wide Range of Current Ratings:
MCCBs are available in a wide range of current ratings, making them suitable for diverse industrial applications. They can handle currents ranging from a few amps to thousands of amps, allowing engineers to choose the appropriate breaker based on the specific requirements of their power distribution system.

Accurate and Reliable Protection:
One of the primary functions of an MCCB is to provide precise and reliable protection against overcurrent conditions. The trip units in MCCBs are designed to respond swiftly to abnormal current levels, effectively isolating the faulty circuit and preventing potential damage to equipment. With adjustable tripping settings, engineers can customize the MCCBs to suit the unique characteristics of their industrial power systems.

Thermal and Magnetic Protection:
MCCBs offer both thermal and magnetic protection, catering to different types of faults. The thermal trip element responds to overloads caused by long-duration, low-level overcurrents, while the magnetic trip element reacts to short-circuit currents. This dual protection mechanism ensures comprehensive safety coverage in industrial power settings.

Selectivity and Coordination: 
Industrial power distribution systems often have multiple levels of circuit breakers, from the main distribution board down to individual branch circuits. MCCBs provide the advantage of selectivity and coordination, which means that when a fault occurs, only the nearest MCCB to the fault will trip, leaving other downstream breakers unaffected. This feature minimizes downtime and optimizes system performance during fault scenarios.

Ease of Maintenance and Retrofitting:
MCCBs are designed for easy maintenance and replacement. With proper periodic inspection and testing, their lifespan can be extended, contributing to cost savings. Additionally, they are compatible with various accessories and digital communication modules, enabling seamless integration into modern industrial automation systems.

Versatility and Applications:
Molded case circuit breakers find applications across various industrial sectors, including manufacturing plants, data centers, commercial buildings, oil and gas facilities, and mining operations. They provide vital protection for motors, transformers, generators, distribution boards, and other critical electrical components.

In conclusion, molded case circuit breakers are indispensable assets in industrial power settings. Their accurate protection, ease of maintenance, and compatibility with modern automation technologies make them a reliable choice for ensuring the safety and efficiency of power distribution systems. By understanding the benefits and applications of MCCBs, engineers can make informed decisions to secure their industrial power infrastructure effectively.

Find the Molded Case Breaker you need here!

It's been a while since we discussed one of our main product categories in an overview post. In the past, we've covered topics like bus plugs to provide general information about the products EMSCO offers. In this post, we'll delve into the basics of Motor Control Centers (MCC).

Shop MCC Buckets and Structure

Shop Medium Voltage Transformers

Shop Molded & Insulated Case Circuit Breakers

EMSCO recently got in more Square D Model-6 MCC structure.

The structure has multiple Size-5 FVNR Starter Plug-On buckets as well as Size-4.

All with solid-state overloads and circuit breaker disconnects.

Whether you need a complete motor control center, an add-on section, or a single bucket we have you covered.

Contact a salesman today.