Morocco Equipment Technician cheat sheet

Ohm's law: V = I × R; power P = V × I = I²R = V²/R. In three-phase systems, P = √3 × U × I × cos φ for balanced loads.

Three-phase line vs phase values: star (Y) connection gives U_line = √3 × U_phase and I_line = I_phase; delta (Δ) gives U_line = U_phase and I_line = √3 × I_phase.

Power factor correction: capacitor bank reactive power Qc = P × (tan φ1 − tan φ2), where φ1 is the initial and φ2 the target angle; target cos φ is typically 0.95–0.98.

Transformer rating is in kVA (not kW) because losses depend on voltage and current, not on load power factor; full-load current I = S / (√3 × U) for three-phase units.

Protection selectivity: the upstream device's time-current curve must lie above the downstream curve with a margin; MCB curve types B (3–5×In), C (5–10×In), D (10–20×In) set magnetic trip thresholds.

Cable sizing depends on four checks: ampacity (Iz ≥ In), voltage drop (≤ 3–5 % typical), short-circuit withstand (k²S² ≥ I²t), and protective conductor sizing.

Motor starting: direct-on-line draws 5–8× rated current; star-delta reduces starting current and torque to one third; soft starters and VFDs limit inrush while controlling torque.

Insulation resistance testing uses a DC voltage (commonly 500 V or 1000 V); values below 1 MΩ on a 400 V installation indicate insulation degradation and require investigation.

Torque–power relation: P (W) = T (N·m) × ω (rad/s) = 2π × n (rev/s) × T; hence T = 9550 × P (kW) / n (rpm).

Belt drives: transmission ratio i = d2/d1 = n1/n2; belt tension should be checked with a tension gauge, and misalignment causes edge wear and vibration.

Gear types: spur (parallel shafts), helical (smoother, axial load), bevel (intersecting shafts), worm (high ratio, self-locking possible, low efficiency).

Bearing codes: the last two digits of a bearing designation give bore diameter in mm × 5 (e.g., 6205 → 25 mm bore); prefix/suffix letters indicate shielding, sealing and clearance class.

Alignment tolerances: coupling alignment uses dial gauges or laser systems; typical acceptable offset is < 0.05 mm and angular misalignment < 0.05 mm/100 mm for precision machines.

Vibration analysis: 1× running speed indicates unbalance, 2× indicates misalignment, high-frequency broadband indicates bearing defects; ISO 10816/20816 zones classify severity.

Lubrication: grease quantity typically 30–50 % of bearing free space; over-greasing raises temperature and can blow seals. Oil viscosity is selected by speed and load per the manufacturer's chart.

Fasteners: torque is applied to a calibrated value; preload depends on friction coefficient, so lubricated and dry threads require different torque values for the same clamping force.

Hydraulic power: P = p × Q, with p in Pa and Q in m³/s; for p in bar and Q in L/min, P (kW) = p × Q / 600.

Cylinder force: F = p × A, where A is the effective piston area; retraction force uses the annulus area (piston area minus rod area).

Flow and speed: cylinder speed v = Q / A; a flow control valve sets actuator speed, while a pressure relief valve sets maximum system pressure.

Pressure relief valve setting is typically 10–15 % above the maximum working pressure of the circuit to protect the pump and components.

Contamination control: ISO 4406 cleanliness codes describe particle counts per mL; most hydraulic systems require ISO 18/16/13 or better, achieved with filters rated in µm absolute (β ratio).

Pneumatics: F = p × A with p in bar and A in cm² giving F in daN; air is compressible, so cylinder speed depends on flow and load, and cushioning is used at end of stroke.

FRL unit order: filter → regulator → lubricator; the regulator adjusts downstream pressure, and the lubricator adds oil mist only when required by the actuator.

Leak diagnosis: hydraulic leaks show as oil trails and pressure drop; pneumatic leaks are found by pressure-decay testing or ultrasonic leak detection, since air leaks are silent and costly.

Foundation checks: verify concrete strength, flatness and anchor bolt positions against the manufacturer's drawing before setting the baseplate; grout only after alignment is confirmed.

Anchor bolts: use the specified grade and embedment depth; torque in the sequence given by the manufacturer, and re-check after grouting and after the first thermal cycle.

Cable routing: respect minimum bend radius (typically 6–12× cable diameter), separate power and signal cables, and use cable glands rated to the enclosure IP class.

Earthing: connect exposed conductive parts to the protective earth with conductors sized per the installation standard; earth resistance is measured and recorded before energization.

Pipe and duct installation: provide expansion loops, correct support spacing, and slope for drainage; align flanges without forcing bolts, which induces stress.

Environmental checks: verify ambient temperature, humidity, ventilation and clearance for maintenance access against the equipment datasheet before final placement.

Documentation at installation: record serial numbers, as-found and as-left conditions, torque values and insulation readings to build the equipment history file.

Commissioning sequence: mechanical completion → alignment → electrical checks → insulation and continuity tests → no-load run → load test → performance acceptance.

Shaft alignment methods: rough with straightedge and feeler gauge, precision with dial indicators (rim and face or reverse dial) or laser alignment; correct soft foot before alignment.

Soft foot: check each foot with a dial gauge while loosening one bolt at a time; acceptable value is typically ≤ 0.05 mm, corrected with shims.

Runout and concentricity: measure with a dial gauge on rotating parts; excessive runout causes vibration and premature seal or bearing failure.

Motor rotation check: verify direction before coupling by bumping the motor; for pumps and compressors, wrong rotation can damage internals.

Baseline data: record vibration, temperature, current, pressure and flow at commissioning to serve as the reference for later condition monitoring.

Acceptance criteria come from the contract and manufacturer's data: pressure, flow, power, noise and vibration must be measured and compared with the specified values.

Maintenance strategies: corrective (after failure), preventive (time-based), predictive (condition-based) and proactive (root-cause elimination); selection depends on criticality and failure consequence.

PM task content: inspection, cleaning, lubrication, tightening, calibration and replacement per the manufacturer's schedule, with intervals adjusted by operating hours and environment.

Corrective workflow: isolate and lock out → diagnose → obtain parts → repair → test → return to service → update records and failure history.

Spare parts policy: classify by criticality and lead time; consumables and long-lead items are stocked, while non-critical items may be purchased on demand.

Lubrication management: use the specified lubricant, clean containers, correct quantity and interval; mixing incompatible greases can cause hardening and bearing failure.

Torque and fastening: reuse of elastic bolts is limited; torque-to-yield bolts must be replaced, and thread-locking compound is applied where specified.

Handover after repair: functional test, safety checks, cleaning of the work area, and a signed work order describing the fault, action and parts used.

Structured troubleshooting: gather symptoms → define the problem → list probable causes → test the most likely and easiest first → confirm the fix → document.

Divide-and-conquer: split the system at interfaces (power supply, controller, actuator) to isolate the faulty block; use substitution with known-good parts only when safe.

Electrical faults: open circuit (no current, full voltage across break), short circuit (overcurrent, blown fuse), and high resistance (voltage drop, heat) are distinguished by voltage and current measurements.

Motor faults: winding resistance imbalance, insulation failure, bearing noise and single phasing are detected by resistance, insulation and current measurements; single phasing causes rapid overheating.

Vibration and thermography: rising vibration or hot spots indicate bearing wear, misalignment, loose connections or overload; trend data is more useful than a single reading.

Root cause analysis: 5 Whys and Ishikawa (fishbone) diagrams separate symptom from cause; the fix must address the cause, otherwise the failure recurs.

Interlocks and safety circuits: a stopped machine may be held by an interlock, emergency stop or limit switch; never bypass safety devices to test operation.

Signal standards: 4–20 mA current loop is preferred for long runs because current is immune to voltage drop; 0–10 V is used for short distances.

4–20 mA scaling: 4 mA = 0 % and 20 mA = 100 % of range; a live zero of 4 mA allows detection of a broken wire (0 mA).

Sensor types: RTD (Pt100, accurate, 100 Ω at 0 °C), thermocouple (wide range, cold-junction compensation), strain gauge (bridge circuit), inductive/capacitive proximity and photoelectric sensors.

Two-, three- and four-wire RTDs: three-wire compensates lead resistance and is common in industry; four-wire gives the highest accuracy in laboratories.

Calibration: compare the instrument reading with a traceable reference at 0 %, 25 %, 50 %, 75 % and 100 % of span, both upscale and downscale, and record error and hysteresis.

Controller tuning: proportional band, integral time and derivative time; too much integral causes oscillation, too much derivative amplifies noise.

PLC I/O: digital inputs read switches and sensors, digital outputs drive relays and contactors, analog inputs/outputs handle 4–20 mA or 0–10 V signals; wiring must match the card's specification.

LOTO sequence: notify affected personnel → identify all energy sources → shut down → isolate → apply locks and tags → release stored energy → verify zero energy → perform work → remove locks and tags in reverse order.

Stored energy: capacitors, springs, elevated loads, pressurized lines and hot surfaces must be discharged, blocked or cooled before work begins.

Lockout devices: each worker applies a personal lock; group lockout uses a lock box, and tags alone are not a substitute for locks.

Risk assessment: identify hazards, evaluate severity and probability, apply the hierarchy of controls (elimination, substitution, engineering controls, administrative controls, PPE), and record residual risk.

Electrical work: verify absence of voltage with a tested voltage detector, work de-energized where possible, and use PPE rated for the incident energy level.

Arc flash and short circuit: keep the approach distance, use insulated tools, and never open an energized enclosure without the required PPE and authorization.

Confined spaces and work at height: permit-to-work, gas testing, ventilation, rescue plan, harness and anchor points are required before entry or climbing.

Drawing types: P&ID (process and instrumentation), single-line diagram (electrical distribution), layout, wiring diagram and isometric; each uses standard symbols defined in the legend.

P&ID reading: instrument bubbles show tag, function and loop number; line types distinguish process, utility and signal lines.

Revision control: documents carry a revision number and status (draft, approved, as-built); work must be performed against the latest approved revision.

Standards families: IEC 60364 for electrical installations, IEC 60204-1 for machine electrical equipment, ISO 12100 for machinery risk assessment, ISO 9001 for quality management.

Nameplate data: rated voltage, current, power, frequency, IP class and insulation class are the reference for installation, protection and spare-part selection.

Compliance records: test certificates, calibration certificates, material certificates and inspection reports form the equipment dossier and must be traceable.

Moroccan context: installations must comply with the applicable Moroccan electrical and safety regulations and the local utility's connection requirements, in addition to the contractual standards.

Work order content: equipment identification, reported fault, diagnosis, actions taken, parts and consumables used, time spent, tests performed and remaining recommendations.

Objective reporting: state measured values and facts, distinguish observation from interpretation, and avoid blaming individuals; the goal is a technical record.

Clear handover: explain what was found, what was done, what remains, and any operating restrictions in plain language suited to the customer's technical level.

Communication during downtime: give the customer an estimated duration and update it when it changes; unexplained delays erode trust more than the fault itself.

Confidentiality and integrity: customer data and drawings are not shared without authorization; conflicts of interest and gifts that could influence decisions are declined or declared.

Continuous improvement: failures and near misses feed back into maintenance plans and spare-parts policy; recurring faults trigger a design or procedure review.

Safety and environment on site: follow the site's permit system, segregate waste (oil, batteries, cables) and leave the work area clean and safe.

Unit conversions: 1 bar = 100 kPa = 10.2 m water column; 1 kW = 1.341 hp; 1 N·m = 0.738 lbf·ft; 1 mm = 0.0394 in.

Measurement uncertainty: record the instrument's accuracy class and range; a reading is only meaningful with its uncertainty and calibration status.

Troubleshooting order for a stopped machine: safety circuit and interlocks → power supply → control signal → actuator → mechanical load.

Before energizing any repaired equipment: insulation test, continuity of protective earth, correct rotation, guards in place, and all locks removed by their owners.

Failure history is the most valuable diagnostic tool: compare current symptoms with previous failures on the same equipment type.

When a fact or value is uncertain, stop and verify with the manufacturer's documentation or a qualified colleague rather than guessing.

A measurement is complete only when it includes the value, the unit, the instrument used, its calibration status and the ambient conditions when relevant.

Repeat a suspect reading with a second instrument or method before acting on it; a single anomalous value is a hypothesis, not a conclusion.

Record as-found and as-left values for every adjustment, so the effect of the intervention can be verified later.

Test records are signed and dated; unsigned or undated records have no evidentiary value in a dispute or audit.

Verification of zero energy is a positive test with a proven detector, not an assumption based on the breaker position.

Test the detector on a known live source before and after the verification test to confirm it works.

Try to start the equipment after isolation to confirm the isolation is effective, with all personnel clear.

Multiple energy sources on one machine must all be identified on the isolation list and locked individually.

Critical spare classification uses failure consequence, lead time and consumption rate; long-lead critical items are stocked even at high cost.

Store parts by the manufacturer's part number, not by description, to avoid wrong-part installation.

Sealed and calibrated items keep their certificate and storage conditions; expired calibration means the item cannot be used for acceptance tests.

Record every part consumed against the work order to keep failure statistics and stock levels accurate.

Report the confirmed diagnosis, the planned action, the estimated duration and the impact on production in that order.

Give a new estimate as soon as the situation changes; silence during a breakdown is interpreted as incompetence.

Do not promise a completion time that depends on an unconfirmed spare-part delivery.

Close the intervention with a written summary the customer can file and use to plan the next maintenance window.

Selectivity between upstream and downstream devices is verified on time-current curves, not by rating alone.

The earth fault loop impedance must be low enough for the protective device to trip within the required disconnection time.

Residual current devices protect people against earth leakage but do not replace overcurrent protection.

Discrimination between RCDs is achieved by time delay and sensitivity: upstream devices are slower and less sensitive.

Clearance fit allows relative motion; interference fit transmits torque by friction and requires heating, cooling or pressing.

Housing and shaft tolerances follow the bearing manufacturer's tables, not general machining practice.

Measure shaft and bore with calibrated instruments and record the actual values before choosing a replacement bearing.

A bearing mounted by impact on the outer ring or through the rolling elements is damaged even if it appears to turn freely.

A 5/2 directional valve has five ports and two positions; a 3/2 valve is used for single-acting cylinders.

Meter-in controls cylinder speed on extension by restricting supply flow; meter-out restricts exhaust flow and gives better load control.

A shuttle valve selects the higher of two pressures; a two-pressure valve (AND) passes output only when both inputs are pressurized.

Sequence valves and limit switches coordinate multi-actuator circuits; the sequence must be verified step by step during commissioning.

Each test procedure states the acceptance criterion before the test is performed, so the result is judged objectively.

Test sheets are completed on site, not reconstructed afterwards from memory.

Non-conformities are recorded with the measured value, the criterion and the proposed corrective action.

The commissioning dossier is handed over with the as-built drawings and the final test results.

Vibration and temperature trending detect degradation earlier than periodic overhaul schedules.

The monitoring interval must be short enough to catch the fastest credible failure mode of the equipment.

Alarm levels are set from the commissioning baseline plus the standard severity zones, not from a generic number.

A trend change is investigated even when the absolute value is still within the alarm limit.

A blown fuse with a short circuit indicates a downstream fault; a fuse that fails without a fault suggests overload or a loose connection.

A motor that trips on overload after a few minutes may be single-phased, mechanically overloaded or badly ventilated.

High contact resistance at a terminal shows as local heating and voltage drop under load, not necessarily at no load.

Insulation resistance that falls after the machine warms up indicates moisture ingress or a developing winding fault.

A pressure transmitter is mounted with its impulse line arranged to avoid gas pockets or sediment traps depending on the process fluid.

A temperature sensor must be immersed in the process to the specified depth to avoid conduction error through the well.

Proximity sensors are mounted with a gap within the manufacturer's sensing range and away from metal that would alter the field.

Shielded signal cable is grounded at one end only to avoid earth loops.

The risk assessment identifies the hazard, the hazardous situation, the possible harm and the persons exposed.

Each control measure is assigned an owner and a completion date, otherwise the assessment remains a paper exercise.

Residual risk is recorded after controls, and the work proceeds only if that residual risk is acceptable.

The assessment is reviewed when the equipment, the procedure or the personnel change.

The IP code gives ingress protection: the first digit is solids, the second is water (IP65 = dust tight, water jets).

The insulation class (F, H) defines the maximum winding temperature rise the motor is designed for.

The duty rating (S1 continuous, S2 short-time) limits how long the equipment may run under load.

The nameplate is the reference for protection settings and spare-part selection; a mismatched replacement invalidates the design assumptions.

Report measured values with their units and the instrument used; a number without a unit is not a result.

State the acceptance criterion next to the measured value so the reader can judge conformity immediately.

Describe the fault in the equipment's own terms (tag number, component, symptom) rather than in vague language.

Recommendations are separated from facts and marked as proposals for the customer's decision.

The work plan identifies the isolation points, the stored energy, the access method and the emergency arrangements before work starts.

Permits to work are issued by the responsible person and closed only when the work is finished and the area is safe.

Toolbox talks confirm that every worker understands the task, the hazards and their role.

Stop-work authority applies to every worker: anyone may stop the job when conditions become unsafe.

Measure pressure at the test point with a gauge of suitable range; a gauge used near its full scale is more accurate than one used at 5 % of scale.

Compare the measured pressure with the relief valve setting and the load requirement to locate restrictions or internal leakage.

A pressure that rises slowly or falls under load indicates pump wear, a leaking relief valve or an internal cylinder leak.

Never adjust the relief valve without the manufacturer's setting and a calibrated gauge.

Check winding resistance phase to phase and insulation to earth before energizing a repaired motor.

Verify the supply voltage and frequency against the nameplate; a VFD-fed motor must be rated for inverter duty.

Check the direction of rotation before coupling and confirm the encoder or resolver alignment after replacement.

Record no-load current and compare it with the expected value; a high no-load current suggests a winding or rotor problem.

Every test certificate references the equipment tag, the procedure revision and the instrument used.

Calibration certificates are valid only within their stated period; expired certificates invalidate acceptance tests.

As-built drawings reflect the installation as it is, and deviations from design are recorded with an approved change note.

The equipment dossier is handed to the customer at acceptance and kept for the life of the installation.

Follow the customer's site rules even when they are stricter than your own company's procedures.

Do not operate equipment outside your authorization or competence; request the qualified person.

Declare any conflict of interest before advising on a purchase or a supplier choice.

Leave the work area clean, segregated and safe; waste oil and batteries go to the designated collection point.

Record the operating conditions (load, temperature, speed) with every diagnostic measurement, because readings are only comparable at similar conditions.

Photograph the fault condition and the repair before closing the equipment.

Compare the reading with the commissioning baseline and with the manufacturer's limits.

A diagnosis is confirmed only when the corrective action removes the symptom and the measurement returns to the expected value.