Product Overview
Cehco 350CR120 Stud-Mount SCR - 350A 1200V Thyristor for Industrial Power Control
Condition
Used, visually inspected, and in excellent condition. Markings on the ceramic insulator collar confirm "CEHCO 350CR120 9243." Threaded stud, hex nut, and copper lug ring terminal show light surface oxidation; no damage or deformation observed. Sourced from a government research facility. Evaluation: Visual inspection only. Function testing not performed.
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Product Overview
Cehco 350CR120 is a stud-mount Silicon Controlled Rectifier (SCR) - a unidirectional thyristor rated for 350 amps forward current and 1200V peak inverse voltage. Designed for high-power industrial applications where precise gate-triggered switching of large currents is required. The stud-mount package with threaded stud, ceramic insulator collar, and ring-terminal lead wire suits panel and heatsink mounting in power control assemblies. Date code 9243 is visible on the body.
Key Features
- Maximum forward current: 350 Amps
- Peak inverse voltage (PIV): 1200 Volts
- Stud-mount package with threaded stud and hex nut
- White ceramic insulator collar visible on body
- Red-jacketed lead wire terminating in flat copper lug with single mounting hole
- Unidirectional device - conducts anode to cathode only
- Gate-triggered turn-on via small control pulse
- Date code 9243 confirmed on body markings
Applications
- Maintenance tech pulls a failed SCR from an electroplating rectifier, confirms the 350A and 1200V ratings match, and installs the 350CR120 to get the bath line running again before the shift ends.
- Repair shop technician diagnosing a downed industrial motor drive traces the fault to a shorted SCR and swaps in the 350CR120 as a direct replacement to restore the drive's DC bus control.
- Industrial fabricator integrating a custom high-power heating control module selects the 350CR120 for its stud-mount form factor and 1200V blocking capability to fit a compact heatsink assembly.
- Maker or power electronics experimenter building a high-current variable DC supply uses the 350CR120 as the controlled switching element in a phase-angle rectifier circuit, firing it from a small gate pulse generator.
- Hobbyist constructing a spot welder or battery-discharge load bank uses the stud-mount body for easy bolt-down heatsinking and the ring-terminal lead for clean, secure wiring at high current levels.
Frequently Asked Questions
What are the key electrical ratings for this SCR?
Maximum forward current is 350 Amps and peak inverse voltage (PIV) is 1200 Volts. These are the primary ratings confirmed for the Cehco 350CR120.
Is this a bidirectional device - can it control AC power directly?
No. The 350CR120 is a unidirectional SCR - it conducts in one direction only, from anode to cathode. For full-wave AC power control, two SCRs in anti-parallel or a bridge rectifier configuration is required. For inherently bidirectional AC switching, a TRIAC is the appropriate device class.
What does the gate terminal require to turn the SCR on?
A small positive current pulse applied between the gate and cathode terminals will trigger conduction. Once triggered, the load current through the device must exceed the latching current to sustain the on-state after the gate signal is removed. A firing circuit or gate driver designed for SCRs handles this in practice.
Does this include a heatsink?
No heatsink is included. The stud-mount package is designed to bolt directly to a chassis, bus bar, or external heatsink. Thermal management is the buyer's responsibility based on their application's power dissipation requirements.
Has function testing been performed?
No. Evaluation is visual inspection only. The unit shows no visible damage and was sourced from a government research facility.
A heavy-iron thyristor from an era when 350 amps meant serious hardware - and it still does. Give it a heatsink and a gate pulse, and this Cehco is ready to go back to work.
