In the field of industrial transmission, Allen Bradley's 1336 PLUS series frequency converters are widely used in motor drive applications ranging from 0.37kW to 448kW due to their stable performance, flexible control methods, and powerful sensorless vector control capabilities. Although the series has gradually withdrawn from the market, the 1336 PLUS remains a must-have equipment for engineers in a large number of old production lines, renovation projects, and spare parts replacement scenarios. This article will systematically review the installation points, control wiring, parameter programming logic, startup and debugging process, and troubleshooting methods for common fault codes of the 1336 PLUS inverter based on the original user manual, providing a complete technical reference for on-site maintenance and fault diagnosis.
Safety first: preparation before installation that cannot be ignored
Any inverter operation must prioritize safety. The 1336 PLUS manual repeatedly emphasizes:
Residual voltage hazard: After the main circuit is powered off, it is necessary to wait for the DC bus capacitor to discharge before any internal operations can be carried out. Measure the voltage between "DC+" and "DC -" on the TB1 terminal block and confirm that it has dropped to zero volts.
ESD sensitive components: The frequency converter contains static sensitive components inside, and static protection measures must be taken during installation, testing, or maintenance (such as wearing a grounding wristband and and using an anti-static workbench).
Only professional personnel are allowed to operate: Only personnel familiar with 1336 PLUS and related mechanical equipment can install, debug, and maintain it.
Software version compatibility: For frequency converters with a power of 45kW or above, the software version must not be lower than 1.07, otherwise it may cause equipment damage or personal injury. Different power levels correspond to different minimum version requirements, for example, 0.37-0.75kW (200-240V) requires 1.05 or above, while 5.5-11kW requires 1.05 or 1.06, etc.
Installation and heat dissipation: key factors determining long-term operational reliability
The installation of 1336 PLUS frequency converter must strictly follow the requirements of heat dissipation spacing, otherwise overheating may cause overheating faults (F08) or shorten the service life.
Minimum spacing: Adequate ventilation space should be left above and below the frequency converter. For A4 machine frames, if installed on combustible surfaces, a 6.35mm shim must be placed under the feet of the installation; The F frame requires a distance of at least 152.4mm from the installation wall on the back and at least 76.2mm from other equipment on both sides.
Environmental conditions: The ambient temperature for IP20 (NEMA 1) enclosed drives is 0-40 ° C, for open drives (IP00) it is 0-50 ° C, and the relative humidity is 5-95% without condensation. If the altitude exceeds 1000 meters, it needs to be downgraded for use.
Heat sink inspection: Regularly clean the dust on the heat sink to ensure that the cooling fan is working properly. The manual provides dissipated power data for each rack, which is used for thermal calculation when users bring their own cabinets.

Main circuit wiring and selection of protective devices
1. Power supply and grounding
1336 PLUS is suitable for symmetrical three-phase power supply, and the phase voltage imbalance should not exceed 3%. For asymmetric or poorly grounded distribution systems (such as corner grounding systems), it is strongly recommended to use isolation transformers and ground the secondary neutral point.
Grounding: A dedicated grounding terminal PE (located on the TB1 terminal block) must be used. The grounding impedance must comply with local electrical codes (NEC, VDE, etc.). When multiple frequency converters share a cabinet, a single point grounding bus should be used. The shielding layer of the control signal should be connected to the TE (true) terminal, which needs to be separately led to the ground and should not be mixed with PE.
Input fuse: The fuse specified in Table 2. A of the manual must be used, otherwise the short-circuit protection performance cannot be guaranteed. The frequency converter is suitable for circuits with a maximum symmetrical current of 200000A and below 600V.
2. Power side reactor and filter
When the capacity of the power transformer is greater than 10 times the rated capacity of the frequency converter, or when there is power factor compensation capacitor switching on the power supply side, it is recommended to install a 5% input reactor or isolation transformer to suppress harmonics and voltage spikes.
When complying with the CE EMC directive, an RFI filter (see Appendix C) must be selected and shielded cables must be used.
3. Precautions on the output side
Motor cable length: Due to the phenomenon of reflected waves, long-distance cables will generate voltage doubling at the motor end, damaging the motor insulation. 1336 PLUS provides the maximum cable length without external devices for different machine frames and voltage levels. For example, for 380-480V drives, if no components are added, A/B shelves usually allow for 30-50 meters; Exceeding the limit requires the installation of output reactors (1321 series) or cable terminations (1204-TFA1/TFB2).
It is strictly prohibited to connect power factor compensation capacitors or surge suppressors on the output side.
If a contactor needs to be installed on the output side, it must be ensured that the inverter output is blocked through auxiliary contacts when the contactor is disconnected, otherwise the inverter will still output dangerous voltage.
Control and signal wiring: precise interface configuration
1336 PLUS offers multiple control interface options: TB2 terminal block (standard analog/digital I/O) and optional control interface board TB3 (L4/L5/L6 and L4E/L5E/L6E with encoder feedback).
1. TB2 terminal (standard control signal)
Terminal signal description
1, 2, and 3 external speed potentiometers (10k Ω) provide 0-10V settings
4,5 0-10V analog input impedance 100k Ω
4-6 4-20mA analog input impedance 250 Ω
7,8 pulse input 5V TTL, maximum 125kHz, used for frequency setting or encoder feedback (choose one)
9. Analog output 1 can be jumper selected from 0-10V or 0-20mA, monitor output frequency or current
10-11, 11-12, 13-14-15, 16-17-18 Programmable Relay Output (CR1-CR4) Resistive Load 5A/115V AC or 30V DC, Inductive 2A
2. TB3 Control Interface Options (Input Mode)
TB3 selects different control combinations through the [Input Mode] parameter (P21), supporting two-wire system, three wire system, multi-stage speed, jog, PID enable, etc. Common modes include:
Mode 1 (default): 2-wire forward/reverse start, stop/fault reset, auxiliary input (normally closed, reports F02 Aux Fault when disconnected).
Mode 2/3/4: Three wire start/stop button control.
Mode 7/8/9: Multi speed selection (up to 7 preset frequencies).
Modes 12-16: Includes digital potentiometer (MOP) acceleration and deceleration control.
Important: After modifying the [Input Mode], the inverter power must be completely disconnected and the bus voltage must be reset to zero before the new configuration can take effect after being powered on again.
3. Encoder feedback wiring (L4E/L5E/L6E options)
The encoder must be line driven (5V TTL or 8-15V), supporting single ended pulse or differential orthogonal signals, with a maximum frequency of 125kHz. The wiring terminals are 31-36 of TB3. The encoder power supply voltage (5V or 12V) needs to be selected through jumper JP3/JP4. When using encoder feedback, the [Speed Control] parameter must be set to "Encoder Fdbk" (value 4), and [Pulse/Enc Scale] must be set to the number of pulses per revolution of the encoder.
Parameter programming logic and detailed explanation of key parameters
1336 PLUS groups hundreds of parameters by function, greatly simplifying debugging. The main groups include: Setup, Advanced Setup, Frequency Set, Feature Select, I/O Config, Faults, Motor Control, etc.
1. Basic operating parameters (Setup group)
Parameter Range Factory Value Description
[Minimum Freq] (P16) 0-120Hz 0Hz Minimum output frequency
[Maximum Freq] (P19) 25-400Hz 60Hz Maximum output frequency, cannot be changed during operation
[Accel Time 1] (P7) 0.0-3600.0s 10.0s Acceleration time (0Hz → [Maximum Freq])
[Decel Time 1] (P8) 0.0-3600.0s 10.0s Deceleration time
[Top Select 1] (P10) Coast/DC Brake/Ramp/S Curve/Ramp to Hold Coast Stop Method
[Current Limit] (P36) 20-160% 150% current limit amplitude
[Overload Amps] (P38) 20-115% drive rated 115% motor thermal overload protection current (set as motor nameplate FLA)
2. Sensorless vector control and V/f selection
For firmware versions 4.01 and above, select the control mode through [Control Select] (P9):
Sens Vector (default): sensorless vector control, providing high starting torque and speed accuracy.
Economy: Energy saving mode, automatically reduces output voltage under light load.
Fixed Boost: V/f control with fixed voltage boost.
Full Custom: Customize the V/f curve by setting [Break Frequency]/[Break Voltage], [Base Frequency]/[Base Voltage], etc.
In sensorless vector mode, to improve performance, the motor nameplate parameters should be input: [Motor NP Amps] (P191), [Motor NP Volts] (P190), [Motor NP Hertz] (P178), [Motor NP RPM] (P177). Automatic tuning can also be performed (manually recorded through [Flux Amps Ref] and [IR Drop Volts]).
3. Frequency given source and multi-stage speed
The frequency source is determined by [Freq Select 1] (P5), [Freq Select 2] (P6), and Speed Select input (TB3). Default [Freq Select 1]=Adapter 1 (i.e. HIM), [Freq Select 2]=Preset 1. By combining Speed Select 1/2/3, 7 preset frequencies ([Reset Freq 1-7]) can be called.
Practical tip: If using a 4-20mA signal as a given, you can enable [4-20mA Loss Sel] (P150) to define the behavior when the signal is lost (stop, hold, switch to minimum frequency, etc.).
4. Flying Start
Used to capture motors in free rotation and avoid overcurrent faults. Enable through [Flying Start En] (P155), with options for "Speed Search" (search starting from maximum frequency or set frequency), "Use Encoder" (use encoder), or "Track Volts" (detect residual voltage). Set the search start frequency in conjunction with [FStart Forward] and [FStart Reverse].
5. Process PID Control (Process PI)
When [Speed Control] (P77) is set to "Process PI" (value 7), the frequency converter can be used as a process controller. Set the source [PI Ref Select] (P215) and feedback source [PI Fdebk Select] (P216) to choose from 0-10V, 4-20mA, pulse, MOP, etc. The proportional gain [KP Process] (P222) and integral gain [KI Process] (P221) are adjustable, and the output is limited to [PI Pos/Neg Limit] (P224/P223). It is also possible to configure integrator preloading, reverse output, etc. through [PI Config] (P213).

Key points for operating Human Machine Interface (HIM)
The 1336 PLUS is equipped with a detachable HIM (with LCD display and control keys). Key operating modes:
Status Display: By default, it displays "Stopped" and output frequency.
Program Mode: Press Enter and select "Program" to enter the parameter group for modification.
Display Mode: Only view parameters and cannot be modified.
Process Mode: Customize the display of two user parameters (set through [Process 1/2 Par] and Scale).
EEPROM Mode: Reset to factory settings or parameter upload/download (Series B HIM only).
Password Mode: Set a 5-digit password to prevent unauthorized parameter modification.
Note: If HIM is removed and the corresponding bit of [Logic Mask] is "1", the frequency converter will report a "Serial Fault". To hot plug HIM, first set the corresponding bit of [Logic Mask] to "0" or disable the control logic through the Control Status menu.
Start debugging process (standard steps)
Chapter 4 of the manual provides a detailed start-up process, with key steps summarized as follows:
Pre power on inspection: Confirm that the main circuit power supply voltage meets the rated value of the frequency converter; Disconnect the motor load; Confirm that the control terminals stop/enable/auxiliary inputs are all closed.
Power on: HIM displays "Stopped". If a fault is reported, record the code and troubleshoot.
Set basic parameters: Enter [Maximum Freq], [Minimum Freq], acceleration and deceleration time, and motor nameplate parameters.
Select control mode (sensorless vector or V/f).
No load test: Start with HIM, set the frequency, and observe whether the output frequency follows. Check if the forward and reverse directions are correct.
Connect the motor load: Reconnect the motor and confirm the rotation direction during low-speed operation. If the direction is incorrect, swap any two output lines (U, V, W).
Encoder polarity check (if used): Compare the polarity signs of [Pulse/Enc Hertz] and [Output Freq], and if they are opposite, swap the A/A - or B/B - wiring.
Sensorless vector tuning: Disconnect the motor from the load, set 45Hz, and record [Flux Current]; Given 0Hz, record [Output Voltage]. Fill in the recorded values in [Flux Amps Ref] and [IR Drop Volts].
Set electronic thermal overload: [Overload Amps] set to motor nameplate FLA, [Overload Mode] select the derating factor (2:1, 4:1, or 10:1) based on the speed range.
Save and exit: If password protection is enabled, execute Logout.

Fault code diagnosis and handling
The 1336 PLUS has a comprehensive fault protection function, and all faults will display brief text on the HIM, while the fault relay will act (CR3, default). The common faults and troubleshooting are as follows:
Common causes and solutions for fault display codes
Auxiliary Fault F02 TB3-24 Auxiliary Input Open Circuit Check External Safety Circuit; If this function is not used, ensure that [Input Mode]=1
Power Loss Fault F03: If the DC bus is below 85% for more than 500ms and [Line Loss Fault] is enabled, check if the input power supply is briefly interrupted; Adjust according to demand [LLoss Restart]
Overvoltage Fault F05 DC bus overvoltage (200V level>405V, 400V level>810V) prolongs deceleration time; Install braking resistor or braking unit
Motor Stall Fault F06: If the current exceeds 150% for 4 seconds, check if the load is stuck; Increase acceleration time
Overload Fault F07 motor overload (I ² t accumulation) reduces load; Check if the [Overload Amps] setting is too low
Overtemp Fault F08: Heat sink temperature>90 ° C, clean the heat sink; Check the cooling fan; Reduce the ambient temperature
Open Pot Fault F09 External Potentiometer Common Terminal Open Circuit Inspection TB2-1/2/3 Wiring
Overcurrent Fit F12 output instantaneous overcurrent (about 200-300% rated) check for output short circuit and grounding; Check the insulation of the motor; Extend acceleration time
Ground Fault F13 output leakage to ground>100A Check motor and cable insulation to ground
Precharging Fault F19: Input voltage check for incomplete pre charging circuit; Check the pre charging resistor/thyristor
Hertz Err Fault F29 with no effective operating frequency (such as maximum frequency less than minimum frequency, or frequency hopping interval covering all frequencies) check [Maximum Freq], [Minimum Freq], [Skip Freq] settings
Serial Fault F10 SCANPort device disconnected, but [Logic Mask] allows control. If hot plugging is required, set the corresponding adapter mask bit to 0
Replace the bus fuse of Blwn Fuse Fit F58 30kW and above machine frame and check if the IGBT is short circuited
The fault can be cleared through the following methods: power off and restart, HIM's Stop button (with [Flt Clear Mode] enabled), external fault reset input, or sending a clear command through communication. Partial faults (such as overcurrent and grounding) cannot be automatically reset, and hardware issues need to be eliminated.
Special Features and Application Examples
1. Skip Frequency
Used to avoid mechanical resonance points. Set [Skip Freq 1-3] (P32-34) and [Skip Freq Band] (P35), the frequency converter will not continuously stay in this frequency range during operation, but will smoothly pass through during acceleration and deceleration.
2. Electric Potentiometer (MOP)
Adjust the frequency setting through the digital input (Dig Pot Up/Down) of TB3, similar to a motor operator. Select the corresponding [Input Mode] (such as Mode 5, 9, 10, 15). [MOP Increment] (P22) Set the frequency change rate per second. Enabling [Save MOP Ref] (P230) can save the last given value in case of power failure.
3. Acceleration and deceleration of S-curve
Setting [S Curve Enable] (P57) to Enabled and adjusting [S Curve Time] (P56) can make the acceleration and deceleration start and end sections smoother and reduce mechanical impact. When [S Curve Time] ≥ acceleration/deceleration time, the total time becomes twice the original acceleration/deceleration time.
4. Example of Process PID Control
Assuming the need to control pipeline pressure: the pressure transmitter outputs 4-20mA and is connected to TB2-4/6, with the pressure setting value given by HIM. The configuration is as follows:
[Speed Control] = Process PI
[PI Ref Select]=Adapter 1 (HIM setting)
[PI Fdbk Select] = 4-20 mA
[PI Config] Configure based on positive/negative effects
Adjust [KP Process] and [KI Process] to make the response stable
Maintenance and spare parts
Regular inspection: Check the terminal fastening, radiator cleanliness, and fan operating noise at least once a year.
Insulation test: Only conduct a 500V megohmmeter test on the main circuit terminals (R, S, T, U, V, W, PE), and the insulation resistance should be greater than 1M Ω. It is strictly prohibited to conduct voltage withstand tests on the control circuit.
Spare parts information: The spare parts list can be obtained through the Rockwell Automation official website or AutoFax service.
