DC CONTROL MODULE:
The SCR bridge is controlled by the DC Control Module. The module is compact and virtually trouble free. The need for servicing and troubleshooting the module have been eliminated because the module can be quickly replaced. All modules of a kind are interchangeable.
Each module has a safety feature called zero throttle interlock which will not allow any motor to be powered if assigned with the hand throttle advanced. For specific control module details, refer to the information sheet on DC Control Modules.
This is a motor brake, designed to slow the drawworks motors and cathead to a preset cathead speed within 10-15 seconds after driller releases the foot throttle. The dynamic brake circuit connects the drawworks motors to a steel grid resistor bank. The energy in the free wheeling DC motors is dissipated in the grid resistor bank. After the braking cycle is completed, the resistor bank is disconnected from the motor and does not interfere with normal drawworks operation.
Bridges are controlled from the driller's console. The console is located on the drill floor near the drawworks. The console is watertight, constructed with the highest quality stainless steel and is equipped with an air purging valve.
Protective functions built into the bridge circuitry are:
SCR bridge over temperature
Emergency off (Activated by switch on the driller's console)
Shutdown for SCR fuse failure