AutomIQ Automation & Drive Services

Automation terms, in plain English

The words you will hear from drive manuals, fault codes and our technicians, explained simply.

A

Absolute encoder
An encoder that knows the exact shaft position as soon as it powers up, so the machine does not need to home first. Common on servo motors and robots.
Encoder repair
AC drive
Another name for a variable frequency drive (VFD): it controls the speed of an AC motor by changing the frequency and voltage it receives.
VFD repair
Alarm code
A number or short code a drive, CNC or PLC shows when it detects a problem. The same thing as a fault code.
Fault Code Library
Amplifier
In motion control, the power stage that drives a servo motor. Many brands call a servo drive a servo amplifier.
Servo drive repair
Axis
One direction of controlled motion on a machine, such as X, Y or Z on a CNC. Each servo axis usually has its own motor and drive module.

B

Backlash
Play or lost motion in gears, couplings or a ballscrew: the axis moves a little before the load follows. It shows up as position error and poor surface finish on CNC parts.
Backlight
The light source behind an HMI's LCD screen. When it fails the screen goes dark or very dim even though the panel is still running.
HMI repair
Backplane
The board at the back of a PLC rack that carries power and data between the CPU and the I/O modules plugged into it.
PLC repair
Ballscrew
A screw and nut with recirculating balls that turns a servo motor's rotation into precise straight-line motion. Used on most CNC axes.
Battery-backed encoder
An absolute encoder that keeps its multi-turn position with a small battery while the machine is off (common on Fanuc and Yaskawa systems). If the battery dies with power off, the axis must be re-referenced.
Encoder repair
Bearing
The part that lets a motor shaft turn smoothly. Worn bearings cause noise, heat and vibration, and can damage the encoder over time.
Bearing & shaft repair
Brake (holding brake)
A spring-applied brake built into many servo motors that holds a vertical axis in place when power is off. A failed brake can stop a machine from enabling.
Brake repair
Braking resistor
A resistor that turns the energy from a decelerating motor into heat. If it is missing, too small or failed, the drive trips on DC link overvoltage.
Brushes and commutator
On a DC motor, carbon brushes slide on the commutator to feed current to the rotating armature. Brushes wear out and are replaced as part of normal maintenance.
Motor repair

C

Capacitor reforming
Slowly bringing a drive that has been stored for a long time back up to voltage, so its DC link capacitors are not damaged at first power-up.
CNC
Computer numerical control: the controller that runs a machine tool's axes and spindle from a part program. Examples are Siemens SINUMERIK and Fanuc Series 0i / 30i.
CNC control repair
Commutation
Switching current between a motor's windings in step with the rotor's position. In a servo motor this depends on the encoder being aligned correctly.
Component-level repair
Repairing a unit by finding and replacing the failed components on its boards, instead of swapping the whole unit or module.
Contactor
A heavy-duty relay that switches power to a motor or drive. Worn contacts can cause intermittent faults.
Control board
The board that holds a drive's or controller's processor and logic. It tells the power stage what to do.
Controller card
A plug-in electronic board that controls part of a machine or drive, such as a CPU, axis or interface card. Often the part that fails inside a larger unit.
Controller card repair
Cooling fan
The fan that pulls air across a drive's heat sink. A worn or blocked fan is a common cause of overtemperature faults.
CPU module
The processor card of a PLC. It holds the program and runs the machine's logic, reading inputs and setting outputs.

D

DC drive
A drive that controls a DC motor's speed by adjusting the voltage on its armature, usually with a thyristor bridge. Still common on older presses, extruders and winders.
VFD & drive repair
DRIVE-CLiQ
Siemens' digital connection between SINAMICS components: control unit, motor modules, line modules and motors with DRIVE-CLiQ encoders.
Model Code Decoder
Dynamic braking
Stopping a servo motor quickly by shorting its windings through resistors when the drive is disabled or loses power.

E

EMC filter
A filter on a drive's supply that reduces the electrical noise the drive sends back into the mains and into nearby equipment.
Encoder
A sensor on a motor that reports shaft position and speed back to the drive. Servo motors cannot run accurately without it.
Encoder repair
Encoder alignment (offset)
Setting the encoder's zero to match the motor's magnetic position. A misaligned encoder causes poor torque, overcurrent or a motor that will not run.
Encoder repair
EnDat
Heidenhain's digital encoder interface. It sends absolute position and encoder data to the drive over a serial connection.
EtherCAT
A fast Ethernet-based fieldbus widely used for motion control, for example with Beckhoff and many servo drives.
EtherNet/IP
The Ethernet-based industrial network used by Allen-Bradley (Rockwell) PLCs, drives and I/O.
Exchange unit
A tested replacement unit you get in exchange for your failed one, usually at a lower price than buying a refurbished unit outright.
Exchange program

F

Feedback cable
The cable that carries encoder or resolver signals from the motor to the drive. Damaged feedback cables are a common cause of encoder faults.
Custom cables
Fieldbus
The network that connects a PLC or CNC to drives, I/O and other devices, such as PROFIBUS, PROFINET, EtherNet/IP or EtherCAT.
Firmware
The software stored inside a drive, CNC or PLC. The firmware version often has to match the rest of the machine for a replacement to work.
Following error
The difference between where a CNC or motion controller commands an axis to be and where it actually is. If it gets too big the control raises an alarm.
Fault Code Library

G

Ground fault (earth fault)
Current leaking to earth through damaged insulation in a motor, cable or drive. Drives trip on it to protect people and equipment.
Fault Code Library

H

Heat sink
The finned metal block that carries heat away from a drive's power transistors (IGBTs). Dust build-up on it causes overheating.
Hiperface
SICK's encoder interface that combines analog sine/cosine signals with a digital data channel. Used on many servo motors.
HMI
Human-machine interface: the touch screen or operator panel used to run and monitor a machine.
HMI repair
Homing (reference point)
Moving an axis to a known reference position after power-up so the control knows where it is. Needed with incremental encoders.

I

I/O module
A PLC card that connects inputs (sensors, switches) and outputs (valves, lights) to the controller.
PLC repair
IGBT
Insulated-gate bipolar transistor: the power switch in most modern drives. Shorted IGBTs are one of the most common drive failures.
Incremental encoder
An encoder that counts pulses as the shaft turns. It only knows position relative to where it started, so the axis usually has to home after power-up.
Industrial PC
A rugged computer built for machines and control cabinets, often with a built-in touch screen.
Industrial PC repair
Inertia ratio
The load's inertia divided by the motor's inertia. A high ratio makes a servo axis harder to tune and can cause vibration.
Insulation resistance test
A test that puts a high DC voltage between a motor's windings and its frame to check the insulation. Often called a megger test, after the instrument.
Motor rewinding
Inverter
The output stage of a drive that turns DC back into variable-frequency AC for the motor. Also used as another name for a whole VFD.
IP rating
Ingress protection rating (IEC 60529). The first digit rates protection against dust, the second against water: IP65 means dust-tight and protected against water jets.

L

Ladder logic
The most common PLC programming language. It looks like an electrical relay diagram, with contacts and coils on rungs.
Light curtain
A safety sensor that sends a row of light beams across an opening and stops the machine when any beam is broken.
Safety equipment
Line module
The supply unit in a modular drive system (for example SINAMICS S120) that feeds the DC bus shared by several motor modules.
Line module repair
Line reactor (choke)
A coil fitted on a drive's supply or output to limit current spikes, reduce harmonics and protect the drive.
Linear motor
A motor laid out flat so it moves a carriage in a straight line directly, with no ballscrew or belt.
Linear motor repair

M

Model code (order number)
The full part number of a drive or motor. Each section stands for an option such as size, speed, encoder, brake or shaft.
Model Code Decoder
Motion controller
A controller that coordinates several servo axes so they move together along a programmed path.
Motion controller repair
Motor module
In a modular drive system, the power unit that drives one or two servo motors from the shared DC bus.
Servo drive repair
Multi-turn encoder
An absolute encoder that counts full revolutions as well as the position within one turn, so it knows the axis position over many turns.

N

Nameplate
The label on a drive or motor with its model, serial number and ratings. A clear photo of it is the fastest way to identify a part.
Part Checker

O

Obsolete part
A part the manufacturer no longer makes or supports. Repair or a refurbished unit is often the only way to keep the machine running.
Legacy & obsolete parts
OEM
Original equipment manufacturer: the company that built the machine or made the part, such as the machine builder or the drive brand.
Overcurrent fault
A fault raised when the drive measures more current than allowed. Causes range from a shorted motor or cable to a failed power stage or wrong tuning.
Fault Code Library
Overtemperature fault
A fault raised when a drive's heat sink or a motor's temperature sensor reads too hot. Often caused by fans, dirty filters or overload.
Fault Code Library
Overvoltage fault
A fault raised when the drive's DC link voltage gets too high, usually while a motor is decelerating and returning energy to the drive.
Fault Code Library

P

Parameters
The settings stored in a drive or controller: motor data, limits, tuning and I/O. Always back them up before a unit is removed.
Parameter backup
Phase loss
One of the three supply phases is missing or weak. Drives detect it and trip to avoid damage.
Fault Code Library
Planetary gearbox
A compact gearbox with gears arranged around a central sun gear. Commonly fitted to servo motors to raise torque and lower speed.
Gearboxes
PLC
Programmable logic controller: the industrial computer that runs a machine's sequence and logic.
PLC repair
Power supply unit
The unit that turns incoming mains power into the DC voltages a control system needs, such as 24 V DC.
Power supply repair
Pre-charge circuit
The resistor and relay that slowly charge a drive's DC link capacitors at power-up. If it fails, the drive may not power up or may trip on undervoltage.
PROFIBUS
A fieldbus widely used with Siemens PLCs, drives and I/O. PROFINET is its Ethernet-based successor.
PROFINET
The Ethernet-based industrial network used with Siemens SIMATIC and SINAMICS equipment and many other brands.
Proximity sensor
A sensor that detects metal or other objects without touching them. Used to sense positions, parts and end of travel.
Sensors
PTC / KTY sensor
Temperature sensors built into motor windings. A PTC switches to high resistance when hot; a KTY gives a reading that rises with temperature.

R

Rack
The frame that holds a PLC's power supply, CPU and I/O modules, connected through the backplane.
PLCs & I/O
Rectifier
The input stage of a drive that turns incoming AC into DC for the DC link.
Refurbished
A used unit that has been inspected, repaired where needed, cleaned and tested before it is sold again.
Shop Parts
Regen (regenerative) unit
A unit that returns energy from a braking motor back to the mains supply instead of burning it off as heat in a braking resistor.
Resolver
A rugged analog position sensor used on some servo motors instead of an encoder. Common on older and high-temperature applications.
Rewinding
Replacing a motor's burnt or damaged copper windings with new ones.
Motor rewinding

S

Safe Torque Off (STO)
A safety function that removes power to the motor so it cannot make torque. If the STO inputs are not wired or are open, the drive will not enable.
Safety controller repair
Safety relay
A relay module that monitors e-stops, guard doors and light curtains and safely shuts the machine down when one is triggered.
Safety equipment
Serial number
The unique number of one individual unit. Two units with the same part number have different serial numbers.
Servo drive
The unit that controls a servo motor's torque, speed and position using feedback from the motor's encoder.
Servo drive repair
Servo motor
A motor with built-in position feedback, controlled by a servo drive for precise motion.
Servo motor repair
Servo tuning
Setting a servo drive's gains so the axis responds fast without overshooting or vibrating.
Soft starter
A device that ramps up an AC motor's voltage at start to reduce inrush current and mechanical shock. Unlike a VFD, it does not control speed while running.
Soft starter repair
Solenoid valve
An electrically operated valve that switches air or hydraulic oil to cylinders and actuators.
Pneumatics & hydraulics
Spindle drive
The drive or amplifier that powers a machine tool's spindle motor and controls its speed.
CNC control repair
Spindle motor
The motor that turns the cutting tool or workpiece on a machine tool. Usually driven by a spindle drive or amplifier.
Motor repair
Stepper motor
A motor that moves in fixed steps, usually without position feedback. Common on smaller axes, feeders and indexers.
Stepper motor repair
Surplus
Unused or lightly used stock, often left over from a project or a plant's spares. Inspected before it is listed.
Shop Parts

T

Teach pendant
The handheld control unit used to jog, program and run an industrial robot.
Robotics repair
Test jig
A test setup that runs a unit under real operating conditions on our bench: drives with a motor, motors under drive control.
How we work
Test report
The record of how a repaired unit was tested before it left our bench. Every repair we ship comes with one.
Thyristor (SCR)
A power semiconductor used in DC drives and soft starters to control how much of each AC cycle reaches the motor.
Torque constant (Kt)
How much torque a servo motor makes per amp of current. Listed on the motor's data sheet.
Touch screen (digitizer)
The touch-sensitive layer on an HMI. Resistive screens respond to pressure; capacitive screens respond to a finger. Dead or drifting touch is a common HMI fault.
HMI repair
Turnaround time
How long a repair takes once the quote is approved. Ours is typically 24 to 72 hours.

U

Undervoltage fault
A fault raised when the drive's DC link voltage drops too low, often from a weak supply, a phase loss or a failed pre-charge circuit.
Fault Code Library

V

VFD
Variable frequency drive: controls an AC motor's speed by changing the frequency of its supply. Also called an AC drive or inverter.
VFD repair

W

Winding
The coils of copper wire in a motor's stator. Damaged insulation between windings causes ground faults and overcurrent trips.
Motor rewinding