Rift Valley Updates

How to Read and Interpret an Induction Motor Nameplate
(Using a Real Siemens Motor as Example)

Many electricians see motor nameplates every day, yet few actually read them. That small metal plate contains everything you need to install, protect, operate, and maintain the motor correctly. Let’s break it down using this 30 kW Siemens induction motor as a practical example.

Power Rating (30 kW / 40 HP)
This tells us the motor’s maximum mechanical output at full load. All design decisions — cable size, starter type, breaker rating — must start from this value.

Voltage & Connection (415 V Δ)
The motor is designed to run on 415 V in Delta connection. Connecting it wrongly (for example, Star on full load) will result in poor torque, overheating, or failure.

Current (52 A)
This is the full load current. It is the most important value for setting:
Overload relay
MCCB/contactor size
Cable sizing
Calculator values are secondary — the nameplate current is the reference.

Frequency (50 Hz)
This motor is designed for a 50 Hz supply. Frequency directly affects speed, torque, and losses. Any deviation must be controlled (e.g., with a VFD).

Speed (1500 RPM) & Poles (4)
At 50 Hz, a 4-pole motor has a synchronous speed of 1500 RPM. The rated speed confirms it’s a standard industrial motor with normal slip.

Power Factor (0.82) & Efficiency (86%)
A PF of 0.82 shows the motor draws a reasonable reactive current, while 86% efficiency means most input power is converted into useful work — not heat.

Duty Class (S1)
S1 means continuous duty. This motor is designed to run continuously at rated load without overheating — ideal for pumps, fans, and conveyors.

Service Factor (1.15)
The motor can safely handle about 15% overload for short periods. This is tolerance, not a license for constant overload.
Insulation Class (F) & Ambient Temperature (50°C)
Class F insulation with a 50°C ambient rating means the motor is built to survive high-temperature industrial environments.

Enclosure & Protection (ODP, IP55)
IP55 indicates good protection against dust and water jets. This helps determine where the motor can be safely installed.

Cooling Method (IC611)
This motor uses shaft-mounted fan cooling with proper air paths. Cooling failure equals winding failure — always check ventilation.

Bearings & Lubrication
The nameplate specifies:
Bearing types (6312 ZZ)
Grease type (UNIREX N3)
Relubrication interval (5800 hours)

This is the manufacturer’s maintenance manual — already summarized for you.

Bottom line:
Every motor failure tells a story — and most of those stories start with someone ignoring the nameplate. If you understand the nameplate, you understand the motor.

NCPB Eldama Ravine management on spot Eldama Ravine NCPB on spot check, last Friday, four Lorries were offloaded in the evening, and people were told to come on Monday for distribution.

On Monday morning, when people arrive, the were no fertilisers on place.

Shout out to my newest followers! Excited to have you onboard! Muze Derick Njomo, Naserian Ruth