Q: I would like to incorporate Oriental Motor’s DSC series AC speed control motor and controller in my Industrial Control Panel and need to calculate the SCCR for my system. What is the SCCR for the DSC series controller?
A: What is SCCR? The short circuit current rating (SCCR) refers to the maximum permissible short circuit current a device or system can endure for a short amount of time without causing damage or device/system failure per the UL 508(A) standard for industrial control panels.
According to NEC Article 409 Section 409.2, an industrial control panel is defined as:
An assembly in an enclosure or panel of two or more components:
• In the power circuit, such as motor controllers, overload relays, fused disconnect switches, and circuit breakers
• In the control circuit, such as pushbuttons, signal lamps, selector switches, time-delay switches/relays, switches, control relays
• Or in a combination of the two circuits
Section 409.110 requires the short circuit rating (SCCR) to be labeled on all industrial control panels. To determine the SCCR of the panel as a whole, the SCCR of each power circuit component must be determined.
Since Oriental Motor products comply with the UL 508 “Industrial Control Equipment” standard and UL 508(C) “Power Conversion Equipment” standard we do not list the SCCR rating that is required under UL 508(A).
In order to determine the SCCR rating for Oriental Motor products, we can follow the following guidelines listed under UL 508(A):
The SCCR of individual power circuit components can be determined using three methods:
• Using the label or specification sheet for the component
• Using the assumed ratings listed in Table SB4.1 for unlisted components
• Using the values from testing the SCCR with a short circuit generator
Based on the table above All Oriental Motor speed controllers, brake packs, brushless motor drivers, stepper motor drivers, servo motor drivers, and inverters have a default SCCR of 5kA.
Below is an industrial control panel system example using our DSCI26UA-360A-3V AC speed control motor and controller.
For more information regarding calculating the SCCR of an industrial control panel, please reference the documents attached.
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