Electric Motor, Cooler & Safety Valve Maintenance

Applies to: STS Series (5–30HP) · STSH Series · STSD · STSP · STSP2

Electric Motor Maintenance

Cooling Fin Cleaning (Every 2,000 Hours)

Remove dust accumulated in the cooling vanes between motor cooling fins. Use compressed air blown along the fin channels. Dust buildup prevents adequate motor cooling and leads to premature failure.

Motors Without Grease Nipple

These motors are sealed-for-life and do not require greasing. Bearings must be replaced at the intervals specified in your model's maintenance schedule (typically every 20,000 hours or 30 months). Contact South-Tek for bearing replacement service.

Motors With Grease Nipple

These motors must be greased at the intervals specified on the motor nameplate label. The nameplate specifies the grease type, quantity, and interval — always follow the nameplate, not generic guidance.

⚠ Warning Using the wrong grease type, mixing grease brands, or applying excessive grease will damage motor bearings and void warranty coverage. Always follow the motor nameplate exactly. Never mix grease brands.

Greasing procedure:

1. Record all motor greasing times. Never skip a scheduled interval.
2. Use a grease pump with the exact grease type specified on the motor nameplate.
3. Apply the quantity specified on the nameplate. Excess grease causes bearing overheating and failure.

▲ Attention — STSD / STSP / STSP2 with Inverter (VSD) These models may include a carbon graphite (coal) brush on the motor shaft for motors 148 HP (110 kW) and above. The carbon brush prevents inverter-induced bearing currents that cause premature bearing failure. See the separate Electric Motor Carbon Brush Replacement article for the replacement procedure and schedule.

Cooler Maintenance (Every 4,000 Hours)

Clean the air/oil cooler at scheduled intervals to maintain cooling efficiency. In dusty or dirty environments, clean more frequently.

⚠ Warning Hot air exiting the cooler must not recirculate back into the compressor intake. If cooler cleaning requires cabinet access, ensure the unit is fully de-energized first.

1. Stop the compressor. Lock out by pressing Emergency Stop. De-energize at the main disconnect. Allow the unit to cool.
2. Open the fan shroud side covers by removing their fastening bolts.
3. Using compressed air, blow from inside the cabinet outward to remove dust and debris from the cooler surface. Do not blow debris back into the cabinet interior.
4. Inspect cooler fins for damage, blockage, or oil accumulation. If fins are oil-fouled, contact South-Tek for cleaning service.
5. Reinstall fan shroud side covers and tighten all fastening bolts.

Safety Valve Maintenance (Every 16,000 Hours or 24 Months)

⚠ Warning Never operate the compressor without a functioning safety valve. Safety valves must not be re-adjusted. Damaged or failed safety valves cannot be repaired — replace immediately. Safety valve testing must be performed by trained, authorized personnel only.

Testing Procedure

1. Stop the compressor. Lock out by pressing Emergency Stop. De-energize at the main disconnect.
2. Close the air outlet valve and discharge all compressed air from the separator tank and system. Confirm zero pressure.
3. Remove the safety valve and test it on a suitable calibrated air line. If the valve does not open at the rated pressure marked on the valve body, it must be replaced.
4. Install a new OEM safety valve if the original fails to open at its rated pressure.

Related Articles

• Carbon Brush Replacement
• V-Belt Inspection & Replacement
• Spare Parts Ordering

For parts or technical support, contact South-Tek Systems: [phone] or [e-mail]