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7 min

CCST 02 — Seal-In (Latching) Circuit

ccstladderseal-inmotorlatch

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CCST 02 — Seal-In (Latching) Circuit scenario preview

Briefing

Classic 3-wire motor control: momentary START_PB energises MOTOR_CONTACTOR, which seals in via its own contact. Momentary STOP_PB drops it.

Objectives

  • Latch MOTOR_CONTACTOR on momentary START_PB
  • Seal-in with MOTOR_CONTACTOR parallel branch
  • Drop on STOP_PB

Hints

  • Parallel the MOTOR_CONTACTOR contact with START_PB in the rung condition
  • Series the NC STOP_PB before the coil
  • MOTOR_CONTACTOR := (START_PB OR MOTOR_CONTACTOR) AND NOT STOP_PB

I/O Table

Inputs

START_PB

Start push-button (momentary)

BOOL · %I0.0

STOP_PB

Stop push-button (momentary)

BOOL · %I0.1

Outputs

MOTOR_CONTACTOR

Motor contactor coil

BOOL · %Q0.0

Your program will be tested against:

All test cases run automatically when you submit. Assertions are hidden until you pass.

  1. #1Motor seals in on momentary start

    Motor seals in on momentary start

  2. #2Motor drops on stop

    Motor drops on stop

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Job-readiness and assessment field guide

CCST practical 002 work-order assessment: readiness checklist

Direct answer

The candidate can clarify the symptom, identify documents and authorization, define expected evidence and avoid beginning with an assumed component failure.

Written for controls-technician candidates preparing to convert a maintenance request into a safe, testable instrument task.

a supervised controls-technician practical assessment bench with representative instruments, motor controls and retained diagnostic evidence while studying work-order interpretation, hazard boundary, instrument identity and acceptance planning
System map / 02

NODE 01observable

Role scope

Reported symptom, operating context, asset and tag identity, process hazard, authorization, documents, tools, reference values, tolerance and completion criteria.

NODE 02observable

Skills map

Request through planning, energy and process controls, inspection, measurement, diagnosis, correction, proving and handover record.

NODE 03observable

Core exercise

The named asset can be tested under the approved state and the acceptance criteria distinguish normal from failed behavior.

NODE 04observable

Stretch case

Ambiguous tag, outdated work order, changing process, missing drawing, unavailable reference, expanded scope, handover conflict and repeat fault.

NODE 05observable

Troubleshooting

A request, identity, hazard, authority, document, test-method, evidence or completion mismatch.

NODE 06observable

Portfolio evidence

The plan reviewed under the employer work-management and safety system before physical execution.

Answer surface / 07

What should a controls technician clarify before starting a work order?

Clarify the exact asset, symptom, process state, authorization, hazards, documents, expected values and observable definition of completion.

Why is the reported failed part not proof?

A work request records an observation or hypothesis; measurements must establish the first failed boundary before parts or configuration are changed.