Mersen TR45R Tri-Onic Class RK5 Time-Delay Fuse, 45A 250VAC/250VDC, Ferrule Terminal
The Mersen TR45R is a Class RK5 time-delay fuse from the Tri-Onic series, rated 45A with a dual 250VAC/250VDC voltage rating for use in both AC and DC circuits. Built with ferrule terminal connections and PolyTube insulating body material, this fuse delivers a 200 kA breaking capacity for demanding overcurrent protection in industrial and commercial electrical systems. RoHS compliant construction helps ensure the TR45R meets environmental standards required for professional electrical work.
Key Features
- Ampere Rating: 45A provides precise overcurrent protection for medium-duty electrical circuits and equipment loads.
- Class RK5 Time-Delay: Offers coordinated protection with temporary overload tolerance, reducing nuisance tripping while maintaining safety.
- Dual Voltage Rating: 250VAC/250VDC supports both AC and DC applications in a single fuse design.
- 200 kA Breaking Capacity: High interrupting rating ensures reliable fault current interruption in demanding electrical systems.
- Ferrule Terminal Design: Copper terminals provide secure, low-resistance connections for reliable electrical contact.
- PolyTube Insulating Material: Durable body construction ensures consistent performance and electrical isolation.
- Clip Mounting: Designed for 50/60 Hz systems with a compact 3 in. product length.
- RoHS Compliant: Meets environmental standards for responsible electrical component manufacturing.
Certifications & Compliance
- RoHS Compliant
Technical Specifications
- Rohs Compliant: Yes
Typical Applications
- Industrial Motor Control Centers
- Commercial Electrical Panels
- HVAC Equipment Protection
- Manufacturing Process Equipment
- Power Distribution Systems
- DC Power Supply Protection
Why Mersen?
Mersen delivers proven reliability with RoHS compliant construction and professional-grade Class RK5 time-delay characteristics. The TR45R's dual 250VAC/250VDC voltage rating and 200 kA breaking capacity ensure dependable overcurrent protection across diverse electrical applications, backed by Mersen's commitment to electrical safety and performance standards.
Manufacturer Resources
Mersen Product Catalog
Product Specs
- AC Max I.R./Breaking Capacity: I1:
- 200 kA
- AC or DC:
- AC/DC
- Ampere Rating:
- 45 A
- Body/Insulating Material:
- PolyTube
- Connection/Terminal Material:
- Copper
- Connection Terminal Type:
- Ferrule
- Frequency (Hz):
- 50/60 Hz
- Fuse Class:
- Class RK5
- Mounting Method:
- Clip
- Product Length:
- 3 in
- Product Weight:
- 0.119 lb
- Rated voltage AC UL:
- 250 V
- Rated voltage DC UL:
- 250 V
- Rohs Compliant:
- Yes
- Speed/Characteristic:
- Time Delay
- Product Type:
- Time-Delay Fuse
- Department:
- Electrical
- Product Group:
- Circuit Protection
- Product Subgroup:
- Fuses
Mersen TR45R – Frequently Asked Questions
1) Will the Mersen TR45R fit a standard 250V Class R fuse block, or do I need a rejection clip?
The TR45R is a Class RK5 ferrule fuse with clip mounting and a 3 inch body length, which is the standard 250V, 31-60A Class R case size. It drops into any 250V Class R fuse block or holder, including rejection-style blocks, because Class R fuses carry the annular rejection groove on the ferrule. Note the reverse is not true: if your holder is rejection type, you cannot substitute a plain Class H or K fuse in its place.
2) Can I use the Mersen TR45R on a 125VDC or 250VDC circuit, not just AC?
Yes. The TR45R carries a dual rating of 250VAC and 250VDC, so it protects DC circuits at or below 250VDC as well as AC circuits at or below 250V. That makes it usable on DC power supplies and battery-backed distribution where a lot of RK5 fuses are AC-only.
3) Is a 45A RK5 time-delay fuse the right choice for a motor branch circuit that trips on inrush?
That is exactly what the time-delay characteristic is for. The TR45R holds through motor starting inrush and short temporary overloads instead of opening, while still clearing a short circuit. Fast-acting fuses in the same amp rating will nuisance-blow on the same motor. If you need the fuse to protect a purely resistive or electronic load with no inrush, a fast-acting midget like the Littelfuse BLF Series is the type to look at instead.
4) Can I put the TR45R in a 480V panel?
No. The TR45R is rated 250V AC and 250V DC maximum, so it must not be applied above 250 volts. For a 480V circuit you need a 600V-rated Class RK5 fuse in the equivalent amp rating, and the 600V case size is physically longer, so the fuse block has to match.
5) What is the difference between the Mersen TR45R and the Littelfuse CCMR040 for a motor circuit?
Both are time-delay fuses, but they are different classes and different physical sizes. The Mersen TR45R is a Class RK5 time-delay fuse rated 45 A at 250 VAC/250 VDC with ferrule terminals and a 3 in. body that drops into standard R-class clips. The Littelfuse CCMR040 is a Class CC time-delay fuse rated 40 A, and Class CC uses a much smaller midget-style body with a rejection feature, so it needs a Class CC holder or block rather than RK5 clips. Choose by the holder already in the panel: R-class clips take the TR45R, a CC block takes the CCMR040.
6) Which fuse should I use if the circuit is DC rather than AC?
The Mersen TR45R carries a dual AC/DC rating, 250 V on AC and 250 V on DC, so a single part covers both a 50/60 Hz AC feeder and a DC power supply circuit at 45 A. Among the alternatives, the Littelfuse CCMR040 is a Class CC time-delay fuse at 40 A and the Littelfuse BLF is a 250 V midget fast-acting fuse, both of which are sized and built for different holders. If the panel mixes AC and DC circuits and you want one stocked fuse for both, the TR45R is the one rated for it.
7) Is a Littelfuse AGU or AGA glass fuse an alternative to the Mersen TR45R?
They are not interchangeable. The Littelfuse AGU and the AGA series, such as the 5 A AGA5, are small glass-tube automotive and electronics style fuses, used in inline holders for low-current loads. The Mersen TR45R is a 45 A Class RK5 branch-circuit fuse with a 200 kA breaking capacity and a PolyTube body, intended for panel clips in industrial and commercial distribution. For motor control centers and power distribution, stay with the R-class fuse.
8) We need fuses for a PowerLogic energy meter - does the Mersen TR45R work there?
No. Metering circuits take the small control fuses supplied for them, such as the Square D PowerLogic energy meter fuse pack, a set of three rated 0.5 A at 600 V. The Mersen TR45R is a 45 A Class RK5 fuse rated 250 VAC/250 VDC for branch and feeder protection, so it is both far too high in current and below the meter circuit voltage rating. Order the meter fuse pack for the metering leads and reserve the TR45R for the load side of the panel.
9) What is the TR45R made of, and will it hold up in a hot MCC cabinet?
Body is PolyTube insulating tube with copper ferrule terminals. Copper ends give a low-resistance contact in the clips, which matters in a warm enclosure where a high-resistance joint is what drives heating and eventual nuisance opening. Keep the clips clean and tight and the fuse seats properly on 50/60 Hz systems.
10) Is the Mersen TR45R RoHS compliant for a spec that requires it?
Yes, the TR45R is RoHS compliant, which covers most institutional and government purchasing specs that call for restricted-substance compliance on electrical components.
11) What part number do I order for a 45A Mersen Tri-Onic, and how much does one weigh for shipping a case?
Order Mersen TR45R. Each fuse weighs 0.119 lb, so a box of ten is just over a pound before packaging, useful if you are stocking spares for a fleet of panels.
How fast can I get the Mersen TR45R delivered?
Most orders ship the same day from our distribution partners, with quick delivery throughout the
continental
U.S.
Need it urgently? Contact Us for expedited shipping options.
Can I return it if it doesn’t work for me?
Yes—ZenSupply offers a hassle-free return policy. If the product isn’t the right fit,
reach out to our support team for a return authorization or setup a return by following our return instructions.
Does the Mersen TR45R come with a warranty?
Absolutely. The Mersen TR45R is backed by a manufacturer’s warranty.
For full warranty terms, check the product documentation or Contact Us.
How do I get technical support or installation help for the Mersen TR45R?
You can call, text, or email our expert support team for fast answers. We’re here to help with
product
selection,
installation tips, and troubleshooting. Contact Us
Why buy the Mersen TR45R from ZenSupply?
ZenSupply makes it easy to get the commercial door hardware you need—fast shipping, expert support,
and
rewards on
every order.
Our team is always ready to help you choose the right product for your project.