WTM7-63 2P DC Miniature Circuit Breaker for 550 V DC Systems
The WTM7-63 2P DC Miniature Circuit Breaker puts two poles in series so one device clears 550 V DC, the voltage band where a single pole runs out of arc length. It protects PV strings, battery banks, rectifier feeds and DC distribution boards, and it isolates the circuit by hand when the panel is opened for service.
Pole count follows the system voltage
One pole works to 250 V DC, two poles in series reach 550 V DC, and the same frame extends to 750 V DC at 3P and 1000 V DC at 4P. A string design can move up in voltage without changing breaker family or panel cut-out.
Nine current ratings on one frame
Ratings run 6, 10, 16, 20, 25, 32, 40, 50 and 63 A, all on the C curve. The thermal element holds 1.13 In without tripping and clears 1.45 In within the hour, and the magnetic element trips close to 10 In for cable and equipment faults.
Breaking an arc that has no zero crossing
DC current never passes through zero on its own, so the arc chamber and the contact gap have to do the work that an alternating wave does for an AC breaker. Two poles share the arc voltage, which is the reason the pair carries 550 V DC.
Breaking capacity and insulation
Ultimate breaking capacity is 6 kA with the service capacity at 100 percent of that value, so a cleared fault inside the rating leaves the device fit to switch again. Rated insulation voltage is 1000 V and rated impulse withstand is 6 kV.
Fitting a two-pole breaker into a panel
18 mm per pole gives 36 mm for the 2P body on 35 mm DIN rail. Terminals accept 25 mm² copper at 2.5 Nm, the front is IP20 to a finger, and the feed can enter from the top or the bottom of the device.
Send your DC system voltage, string current and panel space to confirm the WTM7-63 rating that fits, and we will quote from the factory.
