Maintenance Manual Of Rare Earth Permanent Magnet Generator

1. Introduction

1.1 Appearance:
Maintenance Manual Of Rare Earth Permanent Magnet Generator插图
1.2 Inspection test: 

Check if there are external damages when you receive the goods. Check all the data on the nameplate. Spin the shaft by hand, and check the no-load running. 

1.3 Insulation test:

The windings of the PMG may get damp before the first time use. It is necessary to test the Insulation Resistance.

The reference value of insulation resistance at 25℃ is

Ri≧20 × U/1000 (MΩ)   

U= Voltage -V,   P= Power- kw

 【Attention】Discharge immediately after the Insulation test to avoid high voltage hurt.

The reference value decreases by half when the temperature increases by 20℃.

If it does not reach the reference value, please dry the windings.

The drying temperature is 90℃, the drying time is 12~16 hours.

Please open the drain pipes (if have) when drying.

The windings need to re-wiring if they are dipped in seawater.

1.4 Connection:  

Star connection. (Y)

1.5 Grounding:

The PMG must be grounded before it runs. The grounding point is in the terminal box. You can also ground the housing for safe. 

1.6 Rotating direction:

The PMG can run in two directions.  

2. Operation instruction 

2.1. Operation circumstance:

The PMG is for industrial use. The circumstance temperature is from -15℃ to +40℃. The altitude is no more than 1000m.

2.2. Safety factor:

The PMG should be installed and wired by professionals. There should be safety devices to avoid accidents happening. The install position should fit the design.

2.3. Rules:

The PMG could not run overload or over speed. When the PMG is running, the surface temperature of the PMG will not be over 60% of the allowable temperature.

3. Management

3.1. Store:

All the PMG should be stored indoors, dry, shake-proof, and dustproof. The PMG surface without protective layers ( shaft end, flange) should be rust-proof treated. It is recommended that check the PMG periodically, turn the shaft by hand, and avoid the lack of grease and other problems.

3.2. Transport:

For roller bearings, needle bearings, and ball plunger bearings, there should be a tightening device in transportation.

3.3. Weight:

For the same frame size, because the parameters are different, the total weight may be different. You can see the accurate weight in the nameplate.

4. Installation

4.1. Base plate:

The users should prepare the base plate for the PMG. There should be dust-proof lacquer on the base plate. The base plate should be smooth enough and strong enough. Please avoid sympathetic vibration when choosing the dimension.

4.2. Install the foot bolt

4.2.1. Tighten the bolt but leave a 1-2mm gap.

4.2.2. Use proper methods to adjust the PMG concentricity, and then tighten the bolts symmetrically. If the PMG shaft and other devices are in solid connection, after adjusting the PMG concentricity, you should add two position pins to avoid the concentricity being damaged when the PMG is running. 

4.2.3. Use concrete to fasten the bolts, check the PMG installation, and place locating pins.

4.3. Drain holes:

When installing none standard PMG, please check if the drain holes are facing the ground. When moving the PMG or the PMG is not used, if there are closable plastic drain plugs, please close the plugs. When the PMG is in a very dirty place, all the drain holes should be closed.

 4.4. Adjust the installation:

Correct installation could avoid damage and abrasion of the PMG.

 5. Electrical connection

NOTE: To access to this area is for fully qualified and accredited technicians only

Maintenance Manual Of Rare Earth Permanent Magnet Generator插图1

5.1. The terminal box of the PMG could be rotated according to the situation. The no-use inlets should be closed. Besides the main wirings and grounding point, there may be also other wirings such as PT100, and thermistors. You can get the wiring drawings inside the terminal box.

 5.2. When the gap of the terminal box is open, you can see the main terminals. If the PMG is 3-phase 3 wires without the neutral wire, the two left terminals are U phase, the two middle terminals are V phase, and the two right terminals are W phase. Please connect the terminals and cables using copper bolts. (See the drawing below):

Maintenance Manual Of Rare Earth Permanent Magnet Generator插图2

If the PMG is 3-phase with neutral, the three terminals together are three live terminals (U V W), and the separate one is a Neutral terminal. See the drawing below:

Maintenance Manual Of Rare Earth Permanent Magnet Generator插图3

5.3. When connecting wires, make sure that no boles, tools, or sundries get into the PMG.

5.4. When connecting wires, make sure that the wires from two different phases must not connected together.

5.5 Attention: Do not touch the terminals as soon as the PMG stops, because there may be electricity. Discharge the PMG first.  

6. Installation and change

NOTE: To access to this area is for fully qualified and accredited technicians only

 6.1. Outline:

Should be done by specialists using special tools.

 6.2. Bearings:

The bearings are very important. Need heat or other special tools when installing and changing the bearings.

7. Maintenance and lubrication 

7.1. Outline:

Check the PMG periodically, and keep it clean and ventilated. Check the seal rings (such as V- seal rings). Change if necessary. Check the connection situation and bolts. Check the bearings by hearing the noise, measuring the vibration, or monitoring the oil consumption. If something wrong happens, please stop the PMG immediately and find the reason.  

7.2. Lubrication  

7.2.1. The PMG uses ball bearings. Should add the grease regularly. The period of adding the grease is as the table below:

Adding grease period for ball bearings       

Frame sizegrease weight3600 r/min3000 r/min1800 r/min1500 r/min1200 r/min1000 r/min600r/min300  r/min

Adding grease period for roller bearings           

Frame sizegrease weight3600 r/min3000 r/min1800 r/min1500 r/min1200 r/min1000 r/min600  r/min300  r/min
35560g—-—-2200320044005500  60007000

7.2.2. PMG with grease nipples.

Maintenance Manual Of Rare Earth Permanent Magnet Generator插图4

Please open the grease nipple before adding the grease. For vertical PMG, the period is half of the period in table 7.2.1. In table 7.2.1, the value is based on the bearing temperature is 80℃. The value in table 7.2.1 decreases to half when the bearing temperature increases by 15K. If the max temperature of the bearings is 70℃, the value in table 7.2.1 should be double.

Attention: The operating temperature could not be over the allowable temperature of the grease and the bearings. When the PMG is running at high speed or running at low speed but overloads, the period of adding the grease should be shorter.

7.3. Grease:

When adding the grease, high-quality lithium lubricating grease should be used. The viscosity at 40℃ is 100-140CST.   The concentration is NLGL2 or NLGL3. The temperature range is from -30℃ to +120℃. Good quality grease could be got from the grease producers. When the PMG is a high load or high speed, EP grease is needed.  If the bearing temperature is over 80℃, you can use high-temperature grease, this kind of grease usually allows the bearing temperature to be 15K higher.  

7.4. Attention

7.4.1. High-speed PMG: For high-speed PMG (2 poles), check if the fn parameter is high enough. Fn=DM × n  Dm= average bearing diameter(mm),  n= rotate speed (r/min)  

Most grease will stimulate the skin and eyes. Please follow the preventive measures from the grease producers.  

7.4.2. Accessories: Please give the parameters on the PMG nameplate when you order the accessories.

7.4.3. Noise requirements: The noise of the PMG could not be over the sample or the value on the nameplate. For 60Hz PMG, the noise is 3dB(A) higher than the noise of 50Hz PMG.

7.5 Problems and solutions

NOTE: To access to this area is for fully qualified and accredited technicians only

The PMG shakesThe PMG is a misalignment.Re-install the PMG, and align the PMG shaft.
 The load is not symmetricalMake sure the three-phase loads are symmetrical
The noise is largeThe bearings are not in a good situationClear the bearings and add the grease.
  Change a new bearing.
The PMG temperature is highThe PMG is overloadReduce the PMG load.
 The fan is damagedChange a new cooling fan.
The insulation gets worseThe PMG is wetDry the PMG
 The PMG is agingRebuild the stator windings.
The phase voltage is imbalanced.The load is not symmetricalMake sure the three-phase loads are symmetrical
 Poor contactRe-connect the wires

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