Maintenance of electric motors is a planned system of inspections, measurements and preventive maintenance, which is 5-8 times cheaper than emergency repairs and extends the life of the machine by 1.5-2 times. According to PUE and GOST 27.002, maintenance is divided into daily, shift, weekly, monthly and annual. Below is a complete regulation with checklists and real costs, based on the practice of servicing more than 1,200 engines at enterprises in Tashkent and the Tashkent region.
Why do we need maintenance regulations and who approves them
The maintenance regulations are an internal document of the enterprise, approved by the chief power engineer or technical director. It is based on the engine passport, PTE of consumer electrical installations and operating conditions. Without regulations, maintenance turns into a chaotic “repair after a breakdown,” and this is always more expensive than prevention. At our facilities in Tashkent, the introduction of maintenance regulations reduces the cost of repairing the engine fleet by an average of 35-45% within a year.
The regulations must contain: a work schedule, a list of operations, responsible performers, log forms and material consumption rates. One document for all groups of engines, divided by responsibility and operating conditions.
Maintenance schedule: complete table
| Type of maintenance | Frequency | Who performs | Duration |
|---|---|---|---|
| Daily inspection (DI) | Each shift | Operator | 5-10 min |
| Weekly maintenance (TO-N) | 1 time per week | Electrician | 20-30 min |
| Monthly maintenance (TO-1) | 1 time per month | Electrician 4-5 category | 1-2 hours |
| Quarterly maintenance (TO-2) | 1 time every 3 months | Team 2 people | 3-4 hours |
| Annual maintenance (TO-Y) | 1 time per year | Service organization | 6-10 hours |
| Current repairs (TR) | 1 time every 2-3 years | Specialized service | 1-3 days |
| Major repairs (CR) | 1 time every 6-8 years | Specialized service | 5-10 days |
What is included in each type of maintenance
Daily Maintenance (DU)
Performed by the operator at the beginning and during the shift without stopping the engine. The goal is to identify obvious deviations before they lead to an accident.
- Visual inspection of the housing, terminal box, cable entries for damage.
- Checking for the absence of extraneous noise, knocking, or whistling bearings.
- Control the heating of the case (to the touch - it should not “burn” after 2-3 seconds of contact, this is approximately 65-70 °C).
- Vibration control (visually and to the touch - should not be felt as “shaking”)
- Checking for absence of smell of burnt insulation, smoke, sparking.
- Recording ammeter readings in a removable journal.
Weekly maintenance (TO-N)
The electrician carries out a more detailed inspection without disassembling the unit.
- Cleaning the case from dust with compressed air (pressure no more than 2 atm).
- Temperature measurement with a pyrometer at several points of the housing and bearing shields.
- Checking the fastening to the foundation, tightening loose bolts.
- Monitoring the condition of grounding conductors.
- Checking the belt tension (if there is a belt drive).
Monthly maintenance (TO-1)
Includes measuring operations and short-term stop.
- Current measurement in all three phases - the difference is no more than 5%.
- Voltage measurement, symmetry check - asymmetry no more than 2%.
- Measuring insulation resistance with a megohmmeter 500-1000 V (the norm is at least 1 MOhm at 75 °C).
- Checking the condition of the terminal box contacts, broaching.
- Inspection of the drive coupling, belts, pulleys.
- Checking ventilation and cooling systems.
Quarterly maintenance (TO-2)
In-depth inspection with partial disassembly if necessary.
- Vibration control according to ISO 10816 in horizontal, vertical and axial planes.
- Check alignment with a laser device, adjust if necessary.
- Monitoring the condition of bearings using vibroacoustics or shock pulses.
- Adding grease to bearing units (15-30 g per unit, depending on the size).
- Thermal imaging under load.
Annual maintenance (TO-Y)
The most extensive planned event. Often performed by a specialized service organization.
- Complete cleaning of dust, purging of internal cavities.
- Measurement of insulation resistance of windings relative to the housing and between phases.
- Measurement of DC winding resistance (R-333 bridge or digital microohmmeter).
- Complete replacement of bearing grease.
- Checking the tangent of the dielectric loss angle and measuring the capacitance of the windings.
- Control start with measurement of starting current and acceleration time.
- Drawing up a protocol with recommendations for the next period.
How much does maintenance cost and how much does emergency repair cost
The main argument in favor of routine maintenance is economics. Let's compare the costs for a typical AIR160 engine with a power of 18.5 kW.
| Expense item | Scheduled maintenance | Emergency repair |
|---|---|---|
| Work | 1× base cost | 4-6× maintenance cost |
| Spare parts | Only lubricant/consumables | Bearings, windings, sometimes shaft |
| Production downtime | 30-60 minutes planned | From 1 to 7 days |
| Indirect losses | No | Failure of orders, fines, defects |
| Total relative to maintenance | 1× | 15-25× and above |
Real case: at a bakery in Yunusabad, a failure of the dough mixer drive (22 kW motor) on Saturday afternoon cost the enterprise about 32 million soums, taking into account downtime and urgent urgent repairs. Scheduled maintenance, at which an increasing level of vibration was detected six months earlier, would have cost 18 times less.
Who should perform maintenance: your own staff or a contractor
The optimal scheme for most enterprises is hybrid:
- EO, TO-N, TO-1 - by a full-time electrician.
- TO-2 and TO-G - a third-party service organization that has a laser centerer, vibration analyzer, thermal imager and microohmmeter (the cost of such a set of devices is tens of thousands of dollars, it is irrational to keep it at one enterprise).
- Routine and major repairs - only a specialized workshop, for example repair service for asynchronous electric motors or winding rewinding.
For a fleet of crane and elevator machines, a separate agreement is recommended with a service that has experience in these types of equipment - repair of crane engines and elevator engines requires special competencies and certification.
Documents and magazines
Minimum package: operator's shift log, electrician's maintenance log, insulation resistance measurement protocols, engine passport with repair history. Electronic accounting is more convenient: a simple table or CMMS system is enough to see which engine is “overdue” and which operations have been completed.
Checklist for launching regulations at your enterprise
- Make a complete register of engines: type, power, year of manufacture, operating conditions, responsibility.
- Divide the fleet into groups according to criticality (A - without reserve, B - with reserve, C - non-critical).
- Approve the maintenance schedule linked to the calendar and who is responsible.
- Purchase a minimum set of measuring instruments: megohmmeter, current clamps, pyrometer.
- Conclude a contract for maintenance-2 and maintenance-g with a trusted service organization.
- Enter electronic accounting and analyze deviations monthly.
Do you need help with the development of a maintenance schedule or its implementation? Elektromotors engineers will help you create a schedule for your equipment fleet, conduct staff training and undertake in-depth maintenance. Contact us - free visit of a specialist in Tashkent and the Tashkent region.