Description
GYCM8 DC Molded Case Circuit Breaker Overview
The GEYA GYCM8 DC series is a 2-pole molded case circuit breaker (MCCB) built for DC 1000V and DC 1500V systems, covering rated currents from 100A to 400A with a breaking capacity of 20kA. Designed to IEC 60947-2 and GB/T 14048.2, it provides overload and short-circuit protection for solar PV combiner circuits, battery energy storage systems, and other high-voltage DC distribution networks. Two frame sizes are available: GYCM8DC-250 (DC 1000V, up to 250A) and GYCM8DC-400 (DC 1500V, up to 400A).
Working Principle
The breaker combines a thermal element for inverse-time overload protection with a magnetic element for instantaneous short-circuit tripping. When load current exceeds the rated value for a sustained period, the thermal mechanism operates with a long time delay, allowing normal inrush conditions to pass. Under short-circuit conditions, the magnetic mechanism trips instantly and the arc-quenching system interrupts the DC fault within 10ms at the rated 20kA breaking capacity. A “Push to Trip” button on the front cover allows manual verification of the trip mechanism.
Key Features
Non-polarized connection — the breaker protects reliably under reverse current flow and reverse incoming supply. Line polarity can be assigned to either terminal side according to actual wiring needs, without restriction from the product structure.
Compact 2-pole format — the GYCM8DC-250 measures 180×75mm in footprint, and the GYCM8DC-400 measures 215×90mm, keeping panel space requirements low for the voltage class.
Full-rated service breaking — Ics equals 100% of Icu on both frames, so the breaker remains serviceable after clearing a fault at full rated breaking capacity.
Long operating life — mechanical life reaches 8000 operations (GYCM8DC-250) or 5000 operations (GYCM8DC-400), with an electrical life of 1000 operations for both frames.
Harsh-environment capability — rated for -40°C to +70°C ambient, no derating at 55°C working temperature, suitable for altitudes up to 4000m at continuous full load, and resistant to damp heat, salt spray, and mold.
Protection Functions
The GYCM8 DC series delivers long time-delay overload protection and instantaneous short-circuit protection, distributing electrical energy while shielding cables and power supply equipment from overload and short-circuit faults. Rated impulse withstand voltage (Uimp) is 12kV, with rated insulation voltage (Ui) of 1250V (250 frame) or 1600V (400 frame). Selectivity category A applies to both frames.
Installation
The breaker is fixed-mounted through two 4.5mm mounting holes at 141mm centers (GYCM8DC-250) or 172mm centers (GYCM8DC-400). In a typical two-pole DC circuit, both poles are wired in series through the positive and negative conductors, with terminals 1/3 on the supply side and 2/4 toward the load. Because the design is non-polarized, positive and negative conductors may be connected to either pole as the application requires.
Applications
Typical applications include solar photovoltaic power stations, battery energy storage systems (BESS), EV charging infrastructure, DC distribution panels, telecom DC power systems, and industrial DC networks operating at DC 1000V or DC 1500V with load currents between 100A and 400A.
