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Mersen Tri-Onic TRS-R Class RK5 Time-Delay Fuse, 600VAC/600VDC
Model: MER-TRS-1R
Mersen Tri-Onic TRS-R Class RK5 Time-Delay Fuse, 600VAC/600VDCThe Mersen Tri-Onic® TRS-R is a current-limiting, time-delay fuse in Class RK5, engineered for overcurrent protection of motors,...
Mersen
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$51.83
Mersen Tri-Onic TR-R SmartSpot® Time-Delay Fuse, Class RK5
The Mersen Tri-Onic® TR-R is a current-limiting, time-delay Class RK5 fuse engineered for overcurrent protection of motors, transformers, service entrance equipment, feeders, and branch circuits. Rated 125A at 250VAC / 250VDC with a 200 kA AC interrupting rating, this blade-terminal fuse safely rides through the harmless starting and inrush currents typical of today's motor and transformer loads while still clearing true fault conditions fast. Built-in SmartSpot® visual indication lets technicians confirm fuse condition at a glance, speeding troubleshooting and reducing downtime.
Key Features
- Ampere Rating: 125A for coordinated overcurrent protection on motor, transformer, and feeder circuits.
- Time-Delay Characteristic: Class RK5 time-delay design absorbs harmless motor starting and transformer inrush currents without nuisance opening.
- Dual Voltage Rating: Rated 250 V AC and 250 V DC (UL) at 50/60 Hz for flexible AC/DC application.
- Interrupting Capacity: 200 kA AC maximum interrupting/breaking capacity (I1) for high fault-current environments.
- Connection/Terminal Type: Blade terminals with tin-plated copper construction for low-resistance, corrosion-resistant clip mounting.
- SmartSpot® Indication System: Built-in visual indication system allows quick identification of an opened fuse.
- Body/Insulating Material: Durable PolyTube body construction for reliable insulation and mechanical strength.
- Mounting: Clip mounting for standard fuse block and holder compatibility.
Certifications & Compliance
- RoHS Compliant
Technical Specifications
- Indication System: Yes
- ROHS Compliant: Yes
Typical Applications
- Motor Overcurrent and Branch-Circuit Protection
- Transformer Primary and Secondary Protection
- Service Entrance Equipment Protection
- Feeder and Panelboard Circuit Protection
- Commercial and Industrial Electrical Systems
Why Mersen?
Mersen's Tri-Onic® TR-R Class RK5 fuse combines a rugged PolyTube body, tin-plated copper blade terminals, and a 200 kA interrupting rating to deliver dependable, code-compliant overcurrent protection for demanding motor, transformer, and feeder applications. The integrated SmartSpot® indication system gives maintenance teams a fast, reliable way to verify fuse status, helping keep equipment protected and downtime to a minimum in professional electrical installations.
Manufacturer Resources
Mersen Product Catalog
Product Specs
- Connection Terminal Type:
- Blade
- Indication System Type:
- SmartSpot®
- Mounting Method:
- Clip
- Connection/Terminal Material:
- Tin-Plated Copper
- AC Max I.R./Breaking Capacity: I1:
- 200 kA
- Indication System:
- Yes
- Ampere Rating:
- 125 A
- ROHS Compliant:
- Yes
- Frequency (Hz):
- 50/60 Hz
- Rated voltage AC UL:
- 250 V
- Speed/Characteristic:
- Time Delay
- AC or DC:
- AC/DC
- Rated voltage DC UL:
- 250 V
- Fuse Class:
- Class RK5
- Body/Insulating Material:
- PolyTube
- list_batch:
- MERSEN-20260825
- Department:
- Electrical
- Product Group:
- Circuit Protection
- Product Type:
- Time-Delay Fuse
- Product Subgroup:
- Fuses
Mersen TR125RID – Frequently Asked Questions
1) Will a Mersen TR125RID Class RK5 fuse drop into my existing fuse block for a 125A motor circuit?
The Tri-Onic TR-R, model TR125RID, is a 125A Class RK5 fuse with blade terminals and clip mounting, so it seats in standard Class R/RK5 fuse blocks and holders sized for 125A at 250V. Class R blocks have a rejection feature, and the TR-R is an R-class (RK5) body, so it fits those rejection clips. Check that the block itself is rated 250V or higher and 125A.
2) Will this fuse hold through motor starting inrush without nuisance blowing?
That's what the time-delay characteristic is for. The Tri-Onic TR-R is a time-delay Class RK5 fuse, built to ride through the inrush of motor starting and transformer energizing while still clearing a genuine short circuit. If you were previously using a fast-acting midget or glass fuse on that circuit and getting nuisance openings, a time-delay RK5 is the correct swap for motor loads.
3) Can a Littelfuse CCMR040 Class CC fuse replace a Mersen TR125RID RK5 fuse in a motor circuit?
No. The Mersen Tri-Onic TR-R is a Class RK5 time-delay fuse rated 125 A with blade terminals that seat in clip-style fuse blocks. The Littelfuse CCMR040 is a Class CC time-delay fuse rated 40 A. Class CC and Class RK5 use entirely different body dimensions and rejection features, so a CC fuse will not fit an RK5 clip, and 40 A will not carry a circuit sized for 125 A. Both share the time-delay characteristic that rides through motor starting current, but they are not interchangeable in the same holder.
4) How do I tell if a Mersen TR-R fuse is blown without pulling it and testing?
The TR-R carries Mersen's SmartSpot visual indication built into the fuse, so a technician can see at a glance whether the fuse has opened. That saves pulling each fuse and ringing it out with a meter during troubleshooting on a three-phase set.
5) Should I use a Class RK5 fuse or a Class CC fuse for motor protection?
It comes down to amperage and voltage. The Mersen Tri-Onic TR-R is a 125A, 250V Class RK5 time-delay fuse for full-size motor branch circuits, feeders, and service entrance equipment with blade terminals in clip-mounted blocks. Class CC is a small midget-style fuse for low-amp control circuits and small motor taps, typically up to 30A at 600V, such as the Littelfuse CCMR040 Class CC time-delay fuse. Use RK5 for the main load, Class CC for control transformers and small branch taps.
6) What exact part number do I order to standardize 125A RK5 fuses across my building?
Order Mersen part number TR125RID. That is the 125A Tri-Onic TR-R Class RK5 time-delay fuse with SmartSpot indication, 250V AC/DC. Spec that single number for every 125A, 250V fused disconnect in the facility so your spares crib carries one item instead of several.
7) Is a Littelfuse AGU or AGA glass fuse an alternative to the Mersen TR125RID?
No. The Littelfuse AGU series and the AGA series, such as the 5 A AGA5, are small glass tube fuses used for low-current electronic and automotive-style circuits. The Mersen Tri-Onic TR-R is a 125 A Class RK5 branch-circuit fuse with a PolyTube body, tin-plated copper blade terminals, and a 200 kA AC interrupting rating for service entrance, feeder, and motor protection. They serve different parts of a system and share no mounting or rating overlap.
8) What should I use instead of a Mersen TR125RID when the circuit needs a fast-acting fuse rather than time-delay?
The Mersen Tri-Onic TR-R is a time-delay design, chosen specifically so it absorbs motor starting and transformer inrush without opening. For loads that need fast clearing instead, the Littelfuse BLF series is a midget fast-acting fuse rated 250 V in a laminated tube body. The BLF is a midget-size body, not an RK5 blade fuse, so it requires its own block rather than the clip mounting the TR-R uses.
9) Which time-delay fuse should I choose for a small control circuit where the Mersen TR125RID is oversized?
For lower-current branch and control loads, the Littelfuse CCMR040 is a Class CC time-delay fuse rated 40 A, and it keeps the time-delay behavior needed for inrush. The Mersen Tri-Onic TR-R at 125 A, with blade terminals and 200 kA AC interrupting capacity, is sized for feeders, service entrance equipment, and larger motor circuits. Confirm the fuse block in the enclosure is Class CC rejection style before ordering the CCMR, since it will not accept an RK5 blade fuse.
10) Do any alternatives to the Mersen TR125RID offer blown-fuse indication?
The Mersen Tri-Onic TR-R carries the SmartSpot visual indication system, so a technician can confirm whether the fuse has opened without pulling it. Among the alternatives, the Littelfuse CCMR Class CC time-delay series, the Littelfuse BLF midget fast-acting series, and the Littelfuse AGU and AGA glass tube series are identified by their series designation rather than by an indication feature. If at-a-glance status checking is part of the maintenance routine, the TR-R is the one of this group built around it.
11) Will these fuse terminals corrode in a damp mechanical room or outdoor disconnect?
The terminals on the TR-R are tin-plated copper, which keeps clip contact resistance low and resists the corrosion that drives up heating at the clip. The body is PolyTube for insulation and mechanical strength. For an outdoor disconnect, the enclosure rating is still what keeps water off the assembly.
12) Does the Mersen TR-R fuse meet RoHS for our facility purchasing spec?
Yes, the Tri-Onic TR-R is RoHS compliant, which covers most institutional and government procurement checklists on restricted substances.
13) Will a Square D PowerLogic meter fuse pack work in place of a Mersen TR125RID?
No. The Square D PowerLogic energy meter fuse pack is a set of three 0.5 A 600 V fuses intended for metering circuits. The Mersen Tri-Onic TR-R is a 125 A Class RK5 time-delay fuse rated 250 V AC and 250 V DC at 50/60 Hz, used for the power circuit itself rather than instrument wiring. The two are applied at opposite ends of the installation.
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Does the Mersen TR125RID come with a warranty?
Absolutely. The Mersen TR125RID is backed by a manufacturer’s warranty.
For full warranty terms, check the product documentation or Contact Us.
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