MERSEN FUSE 12,5 URD 71 TT F 0250 12,5URD71TTF0250

High-speed aR characteristic fuse rated at 250A for semiconductor protection with integrated striker indication and metric threaded flush ends.

SKU: A300518Alt SKU: PC71UD13C250TFMPN: A300518

List Price £129.62 ex VAT

Your Price (ex VAT)

£129.62

Manufacturer Lead Time Please contact us for a delivery time before you order

Get the best trade prices Trade exclusive

Create a trade account to unlock exclusive pricing, special offers and more.

Quantity:

SUBTOTAL (EX VAT) £129.62

Trade pricing is personalised to your account

Manufacturer Lead Time

£129.62

Why Choose the Mersen A300518 High-Speed Fuse?

The Mersen A300518 (Catalogue No. PC71UD13C250TF) is a Protistor® Size 71 ultra-fast square body semiconductor fuse designed to protect sensitive power semiconductor devices including diodes, thyristors, IGBTs and similar components used in high-power conversion equipment. It is rated at 250A, 1250VAC (IEC) and 1300VAC (UL), with an aR operating class for semiconductor protection.

Designed for demanding industrial applications, the A300518 features a square body Size 71 construction with flush ends, metric threaded terminals and an integrated striker indicator. Silver-plated contact surfaces, high interrupting capacity and low energy let-through (I²t) provide reliable protection for expensive semiconductor equipment.

Key Advantages

Genuine Mersen Protistor® semiconductor protection fuse.
Ultra-fast aR characteristic for semiconductor devices.
250A current rating.
1250VAC IEC / 1300VAC UL voltage rating.
Integrated striker indicator for fuse operation indication.
High breaking capacity for demanding industrial applications.
Silver-plated contacts for excellent conductivity and corrosion resistance.
Suitable for modern power electronics and converter protection.

Key Features

Manufacturer: Mersen
Manufacturer Part Number: A300518
Catalogue Number: PC71UD13C250TF
Series: Protistor® Size 71
Fuse Class: aR High-Speed Semiconductor Fuse
Body Size: 71 Square Body
Construction: Flush ends with metric threaded terminals
Indicator: Integrated striker

Designed for High-Power Semiconductor Protection

The Mersen A300518 is engineered specifically for protecting semiconductor devices operating in demanding power conversion systems. Its ultra-fast aR characteristic limits fault energy before damage can occur to expensive semiconductor components.

Typical applications include variable speed drives, UPS systems, renewable energy converters, industrial rectifiers, battery storage systems, DC drives, welding equipment and other power electronic installations requiring rapid fault interruption.

Typical Applications

Variable frequency drives (VFDs).
Industrial power converters.
UPS systems.
Solar inverters.
Battery energy storage systems.
Rectifiers.
Motor drives.
IGBT and thyristor protection.
Industrial automation equipment.

Technical Specifications

Item number	A300518
Catalogue No	PC71UD13C250TF
Description	Square Body High-Speed Fuse Protistor® Size 71 aR 1250VAC IEC 1300VAC UL 250A With Striker Flush ends metric threads
EAN/UPC Code	3605340329704
Rated voltage AC UL	1300 V
Rated voltage AC IEC	1250 V
Ampere Rating	250 A
AC or DC	AC
Speed/Characteristic	aR
Fuse Size	71
Mounting	Bolted
Clearing I2t At Rated Voltage	72 kA²s
Melting I2t	8.9 kA²s
AC Max I.R./Breaking Capacity	I1: 126 kA
Indication System	Yes
Indication System Type	Striker
Connection/Terminal Material	Silver-Plated Brass
Connection/Terminal Type	Flush ends
Product Width	51 mm
Product Length	74 mm
Product Height	56.5 mm
Sell Pack Quantity	3 EA
Sell Pack Weight	1.545 kg
Sell Pack Width	90 mm
Sell Pack Length	170 mm
Sell Pack Height	70 mm
Product group	Semiconductor Protection Fuses
Body/Insulating Material	Ceramic
Product Weight	0.515 kg
Power Dissipation at Rated Current Value	61 W
HS Code	85351000
Fuse Type	Semiconductor
Fuse Class	aR
Voltage	1250 V

Frequently Asked Questions

What is the Mersen A300518?

The Mersen A300518 (PC71UD13C250TF) is a Protistor® Size 71 ultra-fast aR semiconductor protection fuse rated at 250A for 1250VAC IEC and 1300VAC UL applications.

What does the aR fuse characteristic mean?

An aR fuse provides partial-range ultra-fast protection specifically for semiconductor devices such as IGBTs, thyristors and diodes, helping minimise fault energy before device damage occurs.

What equipment is the A300518 suitable for?

It is commonly used in variable speed drives, UPS systems, industrial converters, renewable energy systems, rectifiers and other power electronic equipment.

Does the fuse include an operation indicator?

Yes. The A300518 incorporates an integrated striker indicator for remote indication or microswitch operation.

Why choose a genuine Mersen Protistor® fuse?

Genuine Protistor® fuses are engineered specifically for semiconductor protection, providing high interrupting capacity, low I²t values and reliable performance in demanding industrial environments.

Trusted Semiconductor Protection

Mersen Protistor® high-speed fuses are trusted worldwide for protecting critical semiconductor devices in industrial drives, renewable energy installations, power conversion equipment and heavy-duty electrical systems.

Item number	A300518
Catalogue No	PC71UD13C250TF
Description	Square Body High-Speed Fuse Protistor® Size 71 aR 1250VAC IEC 1300VAC UL 250A With Striker Flush ends metric threads
EAN/UPC Code	3605340329704
Rated voltage AC UL	1300 V
Rated voltage AC IEC	1250 V
Ampere Rating	250 A
AC or DC	AC
Speed/Characteristic	aR
Fuse Size	71
Mounting	Bolted
Clearing I2t At Rated Voltage	72 kA²s
Melting I2t	8.9 kA²s
AC Max I.R./Breaking Capacity	I1: 126 kA
Indication System	Yes
Indication System Type	Striker
Connection/Terminal Material	Silver-Plated Brass
Connection/Terminal Type	Flush ends
Product Width	51 mm
Product Length	74 mm
Product Height	56.5 mm
Sell Pack Quantity	3 EA
Sell Pack Weight	1.545 kg
Sell Pack Width	90 mm
Sell Pack Length	170 mm
Sell Pack Height	70 mm
Product group	Semiconductor Protection Fuses
Body/Insulating Material	Ceramic
Product Weight	0.515 kg
Power Dissipation at Rated Current Value	61 W
HS Code	85351000
Fuse Type	Semiconductor
Fuse Class	aR
Voltage	1250 V

UK delivery

Delivery options

Free UK delivery on orders over £200 ex VAT. Order in-stock items before 2pm Monday to Friday for next-day delivery.

This product Lead time on request

Please contact us for a delivery time before you order

Standard delivery

£8 ex VAT · free over £200

UK parcel delivery is £8 ex VAT, or free on orders over £200 ex VAT.

Heavier items may be charged at a weight-based or pallet rate, shown at checkout.

Collect from our showroom

Mon–Fri, 8am–5pm

Order and pay online, then collect from our showroom.

Please allow 15–30 minutes after ordering for us to prepare your order.

Northern Ireland, ROI & export

Priced at checkout

We deliver to Northern Ireland, the Republic of Ireland and overseas.

Delivery is calculated at checkout based on your destination.

Orders with mixed availability

Shipped complete

If part of your order is on a lead time, we hold it and send everything together.

Need the in-stock items sooner? Ask us and we can split the delivery.

Business customer returns

Returns & order support

Need to return an item? Find the guidance for your order below, then contact our team before sending anything back.

Stocked items

Request within 30 days

Changed your mind or ordered the wrong item? Request a return within 30 days of receipt. There is no restocking charge.

Items must be unused, in resalable condition and in their original packaging, and returns need our approval first. Return carriage is at your cost, and the original delivery charge is not refunded.

Faulty or damaged items

Tell us as soon as possible

Faulty, damaged on delivery or the wrong product supplied? Contact our team as soon as possible with the details.

We will review the issue and arrange an appropriate resolution under our terms and conditions and your statutory rights.

Made-to-order items

Manufacturer approval needed

Manufactured, configured and special-order products can only be returned with the manufacturer’s approval. Any handling charge is agreed with you when you request the return.

This does not affect claims for faulty goods or items that do not meet the agreed specification.

LED Controls showroom with electrical products on display

Let’s get your return sorted.

Send your order number, product details and reason for return. For faults or delivery damage, include photographs if available. We will confirm the next steps.

Email returns team 01706 242050

The 30-day return request period applies to change-of-mind returns for stocked items. It does not limit your statutory rights for faulty or non-conforming goods.

● Service Agreements

Credit Accounts

Our service agreements are built to support long term procurement relationships. By working closely with engineering teams and procurement departments, we help streamline purchasing processes while ensuring consistent access to critical components and sourcing support when it matters most.

Priority sourcing and supply support

Flexible payment terms for qualifying organisations

Support for engineering, maintenance, and operations

500 +

Stock lines ready to ship

1,000 +

Same day dispatches

3500 +

Customers supported

28 Trusted Manfacturers

● frequently asked questions

Common questions about our products and support

At Led Controls Ltd we help engineers source the right automation and control gear with confidence. below are quick answers to what we are asked most often.

What product ranges do you supply

We supply all leading manfacturers in our industry. we offer next day delivery on most poplour products.

Can you help specify the correct part?

Your content goes here. Edit or remove this text inline or in the module Content settings. You can also style every aspect of this content in the module Design settings and even apply custom CSS to this text in the module Advanced settings.

Do you have stock for urgent orders?

What are your delivery times and costs?

What about warranties, returns and faulty items?

● latest blog

Discover our latest insights and
expert advice

From a Simple Idea to Small Business of the Year: The LED Controls Story So Far…

by admin | Aug 11, 2026 | News

LED Controls is a specialist distributor of factory automation and industrial controls, supplying OEMs, machine builders, panel builders and end users throughout the UK and worldwide. As a trusted UK distributor for many of the world’s leading automation manufacturers, we provide industrial control products, technical expertise and bespoke automation solutions backed by outstanding customer service.

LED Controls: Danfoss Drives Authorised Partner

by admin | Jan 17, 2026 | Product Spotlight

2025 has been a big year for LED Controls, and our blog has expanded accordingly. We've covered a wide range of topics across industrial control and factory automation this year. From core technology explainers and new product releases to panel building best practice...

LED Controls: Your Complete Control Panel Solution