Technical Specifications

FAQ

1. What is the main function of the 1336-SN-SP6A?
The 1336-SN-SP6A is an inverter snubber circuit board used in compatible Allen Bradley 1336 STEF drive systems. Its primary function is to suppress voltage transients and switching spikes generated in the inverter power circuit. During high-speed switching of power semiconductor devices, parasitic inductance and capacitance can produce rapid voltage changes that place additional electrical stress on the inverter components. The snubber circuit helps control these transient conditions, reducing the impact on the associated power devices and supporting stable operation of the drive.

2. Which voltage configurations are supported by the 1336-SN-SP6A?
The 1336-SN-SP6A is associated with 230 V, 460 V, and 575 V configurations of the 1336 STEF drive family. The corresponding motor power ranges are different for each voltage class: 40–50 HP at 230 V, 60–100 HP at 460 V, and 75–100 HP at 575 V. These ratings should be considered together with the complete drive catalog number and frame configuration when selecting a replacement. The voltage class alone should not be used as the only compatibility criterion.

3. Which drive models can use the 1336-SN-SP6A?
The 1336-SN-SP6A is used with compatible 1336 series drive configurations, including 1336 Plus, 1336 Plus II, 1336 Impact, and 1336 Force applications. It is specifically identified as an inverter snubber board for the 1336 STEF family. Because different 1336 drives can use different power configurations and snubber assemblies, technicians should verify the complete drive model, voltage, horsepower rating, frame size, and original circuit board number before installation.

4. What is the difference between an inverter snubber and a converter snubber?
An inverter snubber is associated with the inverter section of the drive, where the DC bus is switched to produce the controlled AC output supplied to the motor. A converter snubber is associated with the input-side converter or rectifier section. Although both types are designed to control electrical transients, they perform their functions in different parts of the power circuit and are not automatically interchangeable. The 1336-SN-SP6A is specifically an inverter snubber board, so a converter snubber with a similar physical appearance should not be substituted without confirming electrical compatibility.

5. What symptoms may indicate a defective 1336-SN-SP6A?
A defective 1336-SN-SP6A may be associated with inverter-related overvoltage faults, abnormal switching behavior, repeated drive trips, unstable operation, or excessive electrical stress within the inverter power circuit. Physical inspection may reveal burned components, discoloration, cracked components, damaged terminals, or signs of overheating. However, these symptoms can also be caused by failed power transistors, DC bus problems, motor cable faults, excessive regenerative energy, grounding issues, or incoming power abnormalities. Therefore, the snubber board should be diagnosed together with the other components of the inverter power circuit rather than being identified as the fault source based on symptoms alone.

6. What should be checked before replacing the 1336-SN-SP6A?
Before replacement, verify the original part number and compare it with the complete drive catalog number. The drive voltage class, motor horsepower range, Frame configuration, and existing inverter circuit arrangement should all be checked. The original snubber board should also be inspected for visible signs of overheating, electrical arcing, cracked components, or damaged connections. If the board has failed catastrophically, the associated inverter power devices and DC bus circuit should also be tested. Identifying and correcting the underlying electrical problem is important because installing a new snubber board without addressing the original fault could result in another failure.

7. What safety precautions are required when servicing the 1336-SN-SP6A?
The 1336-SN-SP6A is installed inside a high-voltage variable frequency drive, so servicing must be performed only after the drive has been properly shut down and electrically isolated. The incoming power must be disconnected according to the applicable lockout/tagout procedure, and sufficient time must be allowed for the DC bus capacitors to discharge. Residual voltage should be measured with suitable test equipment before internal components are handled. Technicians should also use appropriate ESD precautions when working with the PCB. The board should never be removed, installed, or handled while hazardous voltage remains present inside the drive.

8. What should be checked after installing a replacement 1336-SN-SP6A?
After installation, verify that the snubber boards are correctly positioned and securely fastened, and check all associated wiring, terminals, and connections for proper installation. The drive interior should be inspected for loose hardware, foreign objects, damaged wires, or signs of previous electrical damage before power is restored. After safe energization, check the drive for abnormal fault indications and verify that the inverter section operates normally. A controlled startup should then be performed, followed by gradual loading while monitoring drive status, current, voltage, temperature, and protective functions. If inverter faults continue after replacement, further diagnosis should include the power switching devices, DC bus, motor cables, grounding, and regenerative conditions rather than repeatedly replacing the snubber board.