150-C85NBR — SMC-3 Soft Starter, 85A, 200–480V AC, with Internal Bypass

The 150-C85NBR is an 85A soft starter from the SMC-3 series, covering motors up to approximately 45 kW at 480V AC. It controls the voltage applied to the motor during starting, limiting inrush current and reducing mechanical shock on startup. The "R" suffix denotes an internal bypass contactor — once the motor reaches full speed, the bypass closes and routes current around the SCR power stage, eliminating the continuous power dissipation that would otherwise occur through the semiconductors at full load.

At 85A, this is a mid-range device in the SMC-3 family, suited to pumps, fans, compressors, and conveyor drives in the 22–45 kW range. The application range is broad: anywhere that a direct-on-line starter causes problems — tripped upstream breakers from inrush, belt slip on start, pipe hammer in pump systems — the 150-C85NBR provides a clean alternative without the cost or complexity of a full variable-frequency drive.

Specifications

Parameter	Value
Part Number	150-C85NBR
Series	SMC-3
Rated Current	85 A
Input Voltage	200–480V AC, Three-Phase
Control Voltage	100–240V AC (separate terminal)
Motor Power (approx. @ 480V)	Up to 45 kW / 60 HP
Starting Mode	Voltage ramp (soft start)
Soft Stop	Yes (programmable)
Internal Bypass	Yes (closes at full speed)
Start Ramp Time	1–30 seconds (adjustable)
Initial Torque Setting	Adjustable (potentiometer)
Fault Output	1 × relay, Form A
Protection	Phase loss, overtemperature (device only — no motor overload)
Enclosure	IP20 / Open Type
Operating Temperature	−10°C to 40°C (derate above 40°C)
Standards	IEC 60947-4-2, UL 508, CE

Sizing the Soft Starter

The 85A rating applies to normal duty starting — a motor accelerating a standard centrifugal load (pump, fan) within the default ramp time. Applications that demand more from the starter require derating:

Heavy-duty loads (crushers, compressors, high-inertia loads) that require extended ramp times beyond 10–15 seconds generate more heat in the SCRs during starting. Consult the derating curves for start times above 15 seconds.
High ambient temperature: rated at 40°C; above this, output current must be reduced — typically 1.5–2% per degree above 40°C.
Frequent starts: every start heats the SCRs. Duty cycle matters — applications with more than 5–6 starts per hour need a derating check against the thermal model.
Motor service factor: if the motor is continuously loaded above its nameplate rating (i.e., running with a service factor > 1.0), size the soft starter for the actual running current, not the nameplate current.

FAQ

Q: Can the soft starter be used in-line (series) with the motor, or does it need to be wired in a bypass circuit?

The 150-C85NBR is wired in-line (series) with the motor — it's the standard connection method. The internal bypass is inside the unit; no external bypass contactor is needed. The device handles the bypass automatically once full speed is reached.

Q: What is the difference between soft start and a variable-frequency drive for pump applications?

A soft starter controls motor voltage during start and stop only — at full speed, the motor runs directly on the supply frequency. A VFD controls speed continuously throughout operation. If the application only needs reduced inrush and soft stop with no speed variation during normal operation, a soft starter is simpler and less expensive. If variable speed during operation is required, a VFD is necessary.

Q: How is the ramp time adjusted?

Ramp time is set via a potentiometer on the front of the unit — no software required. Adjust, run a test start, observe the acceleration profile, and fine-tune. For the initial setting, start with 5–10 seconds and adjust based on how the load responds.

Q: Can this unit handle a motor with a higher service factor than 1.0?

The soft starter must be sized for the actual running current, including service factor. If a motor's nameplate is 75A but it runs continuously at 85A due to a 1.15 SF application, size the starter for 85A — which would put it at the limit of this unit. Sizing for the actual load current, not just the nameplate, is the correct approach.

Q: Is the fault relay normally energized or normally de-energized?

The fault relay is Form A (normally open). It closes on fault — energizing only when the device detects a fault condition. Wire the NC side of an interposing relay if a normally-closed fault signal is needed in the control circuit.

150-C85NBR New Sealed PLC 150C85NBR Smart Motor Controller