100% New Mitsubishi Programmable Logic Controller PLC FR-A840-00126-2-60 3.7KW

Mitsubishi FR-A840-00126-2-60 | FREQROL FR-A800 3.7 kW 400V Drive — Conformal Coated / CA 0–20mA / 590Hz / Sensorless Vector

Two Suffix Details That Define This Variant

-2 (Conformal coating): The internal PCBs carry a factory-applied polymer film sealing circuit board surfaces against moisture, humidity cycling, condensation, and corrosive airborne contamination. Without conformal coating, repeated humidity cycling causes electrochemical migration — conductive dendrite growth between PCB traces that eventually produces short circuits. The -2 variant is specified for drives in outdoor enclosures, coastal environments, food processing facilities with wash-down operations, pharmaceutical plants, and chemical process environments with airborne acids or alkalis. For standard climate-controlled indoor panels, the non-coated variant is sufficient.

-60 (CA terminal type): In addition to the standard 0–10V voltage reference input, this variant includes a 0–20mA current analogue input. Current loop (4–20mA or 0–20mA) references are more noise-immune than voltage references over long cable runs and in electrically noisy environments — the CA configuration serves installations where the speed reference originates from a remote transmitter, process controller, or PLC analogue output that uses current loop signalling.

Key Specifications

Control Mode Selection

Real sensorless vector (no encoder needed): The default for most applications. The drive computes a real-time motor model from internal current and voltage measurement to maintain stable speed and torque across the full speed range. Requires motor nameplate data entry (rated power, voltage, current, frequency, poles) and best performance from the auto-tuning function. Correct for fans, pumps, conveyors, and compressors where encoder installation is unnecessary.

Closed-loop vector (encoder required): With an optional encoder card and shaft-mounted encoder, speed regulation tightens to ±0.01% and speed control range extends to 1:1500. Used for tension control in winding applications, web-speed synchronisation, and machine tool spindle drives.

V/f: Universal mode — for multi-motor configurations (one drive, multiple parallel motors), very long motor cables where vector model accuracy is uncertain, and retrofits where motor data is unknown.

590 Hz Output Ceiling

The 590 Hz upper limit serves high-speed induction motors in grinding spindles, centrifugal separators, and air-bearing spindles that operate at 200–400 Hz nominal frequency. Most general-purpose inverters cap at 400 Hz — the FR-A840's 590 Hz reaches 30,000–40,000 RPM territory depending on motor pole count, from a standard catalogue product without requiring a specialised high-speed drive.

FAQ

Q1: When is conformal coating necessary, and when is the standard variant sufficient?

Conformal coating is specified for outdoor enclosures, coastal and high-humidity environments, food processing and pharmaceutical facilities with steam or wash-down exposure, and chemical plants with airborne corrosives. For standard climate-controlled indoor industrial panels, the non-coated variant is adequate. If the drive is in a panel that experiences significant temperature swings with condensation risk, the -2 variant reduces risk significantly.

Q2: What are ND, HD, and LD ratings and when does the selection matter?

ND (Normal Duty) at 9A handles 150% overload for 60 seconds — fans, pumps, conveyors with normal starting loads. HD (Heavy Duty) rates the same drive at 6A continuous with 200% overload for 60s — cranes, hoists, extruders, and loads with sustained heavy starting. LD operates at 11.5A with reduced overload for low-overload fan and pump applications. Select ND for most applications; HD when starting torque consistently exceeds 150%.

Q3: What motor data is needed for sensorless vector to work correctly?

At minimum: rated power (kW), rated voltage, rated current, rated frequency, and number of poles. For best performance especially below 10 Hz, run the auto-tuning function (offline, motor stationary, 30–60 seconds) — the drive measures no-load current and primary resistance (R1) and builds an accurate motor model. An inaccurately modelled motor can be unstable at low speed in sensorless vector mode.

Q4: What fault history information is available after a trip?

The FR-A840 stores the most recent eight fault events, each with the fault code and operational parameters at trip time (output frequency, current, voltage, temperature). Access via the operator panel (FR-DU08) or Modbus registers. Reset the drive after clearing the trip condition (correct the fault source, then use the RES terminal or the STOP/RESET key). The fault history distinguishes one-time transient trips from recurring systematic faults requiring engineering investigation.

Q5: What optional communication networks beyond RS-485 Modbus are available?

Optional A8CON option cards add CC-Link (A8CON-CCL), PROFIBUS-DP (A8CON-PBT), DeviceNet (A8CON-DNT), and EtherNet/IP (A8CON-EIP). The same A8CON cards fit the same slot across the FR-A800 frame range — the communication option specified on a 3.7 kW unit is architecturally identical to the same card on a 55 kW unit in the same system.