DC Miniature Circuit Breaker 125A | 1000V DC MCB 10kA
WTM7-125 125 A frame DC miniature circuit breaker: 10 kA Icu, up to 1000 V DC on four poles, 32 to 125 A, B, C and D curves, non-polarised 50 mm² terminals.
DC Circuit breaker
DC-rated breakers built for solar, battery, and DC power systems with stable interruption performance.
DC Circuit breaker products
WTM7-63 4P DC Miniature Circuit Breaker MCB
WTM7-63 4P DC miniature circuit breaker for 1000 V DC: four poles on one handle, 6 kA, C curve, 6 to 63 A, polarity marked terminals, 72 mm body.
WTM7-63 DC Circuit Breaker
WTM7-63 DC Miniature Circuit Breaker (DC MCB) DC Voltage Coverage: Rated voltage from DC 250V in 1P configuration up to DC 1000V in 4P configuration, matching the pole count to the DC system voltage. Complete Ratings Range: Rated current from
WTM7-63 2P DC Miniature Circuit Breaker MCB
WTM7-63 2P DC miniature circuit breaker for 550 V DC strings: 6 kA breaking capacity, C curve, 6 to 63 A, 36 mm body, 25 mm² terminals, 35 mm DIN rail.
Choose the Poles by Voltage
Send the maximum system voltage and the string current. We reply within 24 hours with the model, the pole count and the fuse coordination for the combiner.
DC CIRCUIT BREAKERS
DC Circuit Breakers for Solar Strings and Battery Circuits
A DC breaker does two jobs on a solar array: it protects the cable against a fault, and it gives a way to isolate the string for service. The arc is the hard part, because direct current never passes through zero, so the arc chamber is deeper and the contacts are further apart than in an AC breaker.
The WTM7-63 covers 3 A to 63 A. One pole is rated 250 V DC, two poles in series 500 V DC, three poles 750 V DC and four poles 1000 V DC, with 6 kA short-circuit capacity throughout.
On a 1000 V string, that means the four-pole version, not a single-pole device wired twice. Units carry CE and CCC marking.
Sizing a DC Breaker for a String
Two numbers decide the order: the string current and the maximum system voltage. The pole count follows the voltage, not the current.| System voltage | Poles needed | Current | Typical use |
|---|---|---|---|
| 48–250 V DC | 1P | 3–63 A | Battery cabinets, telecom |
| 500 V DC | 2P | 3–63 A | Small strings |
| 750 V DC | 3P | 3–63 A | Residential inverters |
| 1000 V DC | 4P | 3–63 A | Commercial strings |
Installation notes
- Positive or negative? Fit the breaker in the positive conductor, and keep the same polarity on every string so the isolation point is consistent.
- Size with margin. The breaker has to sit above the string current with allowance for heat in the combiner, and below the cable rating.
- Breaker or fuse? A fuse is cheaper per string and needs no switching; a breaker adds the isolation point that service work needs. Many combiners use fuses per string plus one breaker as the isolator.
Two Numbers Fix the Pole Count
One Pole, 250 V DC
Above that the poles go in series: 500 V for two, 750 V for three, 1000 V for four.
Keep the Isolation Point on One Conductor
Fit the breaker in the positive side and keep it there across every string on the array.
Breaker or Fuse, Not Either-Or
Fuses protect each string; one breaker upstream gives the isolation point that service work needs.
COMMON QUESTIONS
Frequently Asked Questions
Install it in the positive conductor, and keep the polarity consistent across strings so every isolation point is on the same side. Some codes allow switching the negative, but mixing the two on one array makes service work dangerous.
Take the string short-circuit current, apply the margin your code requires, and choose the next rating up that stays below the cable ampacity. Then choose the pole count from the maximum system voltage, not from the current.
A fuse protects the string cable at low cost and needs no switching. A breaker also gives you an isolation point, which matters when a string has to be worked on. Many designs use fuses per string and one breaker as the isolator.
Each pole has a limited arc-breaking capability, and poles in series share the arc voltage. One pole is rated 250 V DC, two poles 500 V DC, three 750 V DC and four 1000 V DC.
No. An AC breaker relies on the current crossing zero to extinguish the arc. On DC the arc sustains, the contacts overheat, and the breaker may fail to clear a fault. Use a breaker rated for DC at your system voltage.
Isolate the string, confirm zero volts with a meter rated for the system voltage, then check continuity across the breaker in both positions. Do not test on a live string; DC arcs do not self-extinguish and the meter leads are not rated for it.
CONTACT US
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Send your application, voltage, certifications and quantity to this electrical protection manufacturer. We reply with a quotation within 24 hours.
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- One order owner from quotation to delivery