CcRD - S/R - 3

 

CCRD - 

PENDULUM SWITCH -

Electrical control reeling drum pendulum limit switch working details

An electrical control reeling drum with a pendulum limit switch works as part of a cable reeling drum (CRD) system used to supply power to moving machines like unwinding a cable automatically.

**Working Details:**

- The cable reeling drum winds or unwinds the cable as the machine moves along its runway, guided by roller guides to prevent cable damage.

- Limit switches, including pendulum-type, are installed to control the drum motor and machine travel, ensuring safe operation.

- The pendulum limit switch acts as a mechanical sensor that detects the cable tension or position by swinging like a pendulum; when it reaches a certain angle or position due to cable movement or tension, it actuates electrical contacts.

- These contacts then send signals to stop or reverse the drum motor or machine travel to prevent over-winding, cable slack, or excessive tension.

- Typical limit switches in the system include over-tension switches (to stop if cable tension is too high), under-tension switches (to detect cable slack), directional sensor switches (to control motor based on travel direction), and geared rotary limit switches (to bypass other switches near the cable feed point).

- The pendulum limit switch is crucial for detecting dynamic cable tension changes and ensuring the cable is properly wound or unwound without damage or risk of machine malfunction.

In essence, the pendulum limit switch converts mechanical movement or tension changes in the cable into electrical signals that control the drum motor and machine travel, maintaining safe and efficient operation of the cable reeling drum system.

RESISTANCE  BOX -

The resistance box of a control cable reeling drum is an electrical component used to manage and limit the current in the system during the operation of the cable reeling drum—a device that automatically winds and unwinds control or power cables on moving machinery such as cranes or hoists.

Description and Function:

Purpose: 

The resistance box is typically used in conjunction with electric motors (usually wound rotor induction motors) that drive the drum. It helps control the starting current and speed of the motor by inserting resistance into the rotor circuit.

Construction:

Made from resistance coils or wire-wound resistors housed in a ventilated enclosure, often with ceramic or stainless-steel elements.

Designed to withstand heat generated during current limiting.
May include taps or steps for varying resistance values, depending on the motor’s speed control requirements.

Operation:
At startup, maximum resistance is inserted to limit the inrush current.

As the motor picks up speed, the resistance is gradually reduced (either manually, through a controller, or automatically) until it is shorted out or minimized.

Application in Cable Reeling Drums:

Ensures smooth cable winding/unwinding.

Prevents jerky movements or cable tension that could damage the drum, cable, or machinery.
Allows speed regulation of the motor driving the drum based on load conditions.

PUMP - 1

Problem and Solution -

1. The CCRD cable is not rotating, so the cable has fallen down at the coalyard center near the JB side point. ( Date : 17/04/2025)

SOLVED  - Again in CCRD, the 3 limit switch for Pendulum  is always normally closed (NC), but the 3 limit switch for Pendulum is loose and the limit switch 3 number is unclear. So after tightening the CCRD pendulum limit switch, it is working smoothly.. 

  ⚠️  ସେଠାରେ ୪ ଟା limit Switch ଲାଗିଛି ୩ଟା Use ହୋଇଛି । ହଁ  ୩ଟି Limit Switch ସବୁବେଳେ NC ରହିବା ଦରକାର ନଚେତ୍ Cable Drum ଗୋଡେଇବ ନାହିଁ। Thank you 🙏🏻