JPS62100148A - Testing method for bearing performance of motor - Google Patents

Abstract

PURPOSE:To decide necessity for inspection and exchange properly and easily by gradually increasing applied voltage from zero by a variable transformer for a power circuit and deciding a holding within the tolerance of a reference data of a voltage value and a current value at that time. CONSTITUTION:A voltmeter 7 and an ammeter 8 are connected previously to the power circuit side of a motor M. Supply voltage applied to the motor M is increased gradually from zero volt by moving variable transformers 5 in a power circuit. The voltage value and current value of the motor M are measure at that time when the motor M starts its revolution, and both values are compared with a previously prepared data. A holding within a tolerance of a difference among both values and the data is judged, thus deciding the presence of the overhaul and exchange of a bearing. Accordingly, the presence of the necessity of the release of the bearing is selected easily, thus reducing the number of the exchange of the bearing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a bearing performance testing method for an electric motor for appropriately determining whether or not the bearing of the electric motor needs to be opened and inspected and replaced.

[Conventional technology]

Conventionally, the following method has been adopted to determine whether or not an electric motor bearing needs to be opened and inspected or replaced.

(a) A method of counting the operating time of the motor using a time counter and determining the life of the bearing from the cumulative time.

(b) A method of conceptually determining aging deterioration of bearings due to the number of years that have passed (for example, two years), regardless of the operating time of the electric motor.

(c) A method of determining whether a bearing is damaged or not based on whether or not an unusual sound is generated during operation of the electric motor.

(d) When the electric motor is used to drive a pump, a method of determining whether there is wear or damage to the bearings based on whether the pump's discharge pressure has decreased abnormally.

(e) A method of measuring the temperature of the bearing and determining whether the bearing is damaged or not based on whether the temperature is abnormally high.

[Problem that the invention seeks to solve]

However, if the motor is for example a motor for driving a submersible pump immersed in liquefied gas in a cargo tank installed on a refrigerated ship, the above-mentioned (a) to (ho) will determine whether bearing opening inspection or replacement is necessary. ) cannot be said to be an appropriate method for determination. That is, the above (a), (b), (
The method (c) requires relying on the inspector's intuition to determine whether the bearing is good or not, and it ends up being replaced before the end of its service life, which is uneconomical. Also, (d).

Method (e) allows you to physically determine whether the bearing is good or bad, but it is not possible to constantly check the electric motor for driving the submersible pump, which is immersed in the liquid in the cargo tank, through the monitoring port. In the end, we have no choice but to rely on methods (a) and (b), and the bearings have to be replaced during inspection.

The present invention uses the voltage and current values at low voltage and low current startup of the motor as criteria for determining deterioration of the bearing, so that even if the motor is a motor for driving a submersible pump, there is no need for open inspection or replacement of the bearing. It is an object of the present invention to provide a bearing performance test method for an electric motor that can appropriately, simply and easily determine the bearing performance of a motor.

[Means for solving problems]

Therefore, in the present invention, when determining whether the bearings of the electric motor need to be inspected or replaced, first, a variable transformer provided in the power supply circuit of the electric motor is used to change the power supply voltage applied to the electric motor from 0V so that the electric motor rotates. When the motor starts rotating, measure the voltage and current values at that time, and then compare the measured voltage and current values with pre-prepared data to determine if the difference is within the allowable range. The feature is that it determines whether or not the bearing needs to be opened and inspected or replaced based on whether or not it is inside.

[Effect]

Therefore, by adopting such a method, abnormalities can be detected before the bearing opening inspection of the electric motor, and it becomes easy to determine whether the bearing is open or not. The immersed submersible pump driving electric motor reduces the number of expensive bearing replacements, and saves bearing and construction costs, making it economical.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

The drawing shows a circuit configuration for testing the bearing performance of an electric motor for driving a submersible pump immersed in liquefied gas in a cargo tank installed on a refrigerated ship. In the figure, 1 is a power transformer (440/40V) whose primary winding is connected to a three-phase AC power supply (not shown) via a no-fuse breaker (NFB) 2, and whose secondary winding is connected to an electromagnetic switch 3. ．． A variable transformer 5 is connected via an overcurrent relay (OCR) 4 in series. This variable transformer 5 includes star-connected phase windings 5a and a slider 5b that slides on each phase winding 5a to adjust the output voltage within the range of, for example, OV to 46V. The sliders 5b for each of the three phases are output terminals tu and tv.

tw, respectively. A submersible pump driving electric motor M immersed in the liquefied gas in the cargo tank is connected to the output terminals tu, tv, and tw. Further, the slider 5b of two phases of the variable transformer 5, in this case U and V phases, and the output terminal tu.

Connect a voltmeter 7 between the electrical circuits connecting the TV and the other phases.

An ammeter 8 is provided in the electrical path connecting the W-phase slider 5b and the output terminal tw. On the other hand, a power indicator light 10 is connected via a fuse 9 between two appropriate phases, in this case, V-phase and W-phase electrical circuits, on the primary side of the power transformer 1 . Further, an operation indicator light 11 is connected in parallel to the power indicator light 10 via an auxiliary normally open contact 3al of the electromagnetic switch 3. Further, the electromagnetic switch 3 is connected to the power indicator 10 through a series circuit of a starting switch SW2, which is connected in parallel with the normally closed contact 4b of the overcurrent relay 4, the stop switch SWI, and the auxiliary normally open contact 3a2 of the electromagnetic switch 3. An excitation coil 3c is connected to the excitation coil 3c.

Next, in the bearing performance test circuit for a submersible pump driving electric motor configured as described above, a method for determining whether or not the bearing needs to be inspected and replaced will be described.

First, the position of the slider 5b of the variable transformer 5 is set to the output terminal ta.
, tb, and tc are adjusted so that they become Ov. Next, when the starting switch SW2 is turned on, the excitation coil 3C of the electromagnetic switch 3 is excited and the electromagnetic switch 3 is turned on, simultaneously closing its auxiliary normally open contacts 3al and 3a2. Therefore, the excitation coil 3C of the electromagnetic switch 3 is self-held by the auxiliary normally open contact 3a2, and both the power indicator light 10 and the operation indicator light 11 are turned on.

Now, when the electromagnetic switch 3 is turned on, voltage is applied from the power transformer 1 to the variable transformer 5, but the output terminals ta and tb
, tc are OV, so no voltage is applied to the submersible pump motor M. From this state, by moving the slider 5b of the variable transformer 5, the output terminals ta,
The voltages of tb and tc are gradually increased until the submersible electric motor M rotates. When the start of rotation of the submersible electric motor M is confirmed, the voltage value and current value at that time are read from the voltmeter 7 and ammeter 8. Next, these voltmeter 7 and ammeter 8
The voltage and current values read from the device are compared with previously prepared data, that is, the respective voltage and current values measured in the same manner as described above when the product was new. And each difference is within the permissible range.

In other words, depending on whether the voltage and current values are within the range when the bearing inspection or replacement time is reached (this also refers to the measurement data at the time), the bearing inspection or replacement is performed. Determine whether it is necessary.

Therefore, by reading the voltage and current values when the submersible electric motor M is confirmed to start rotating and comparing them with the respective voltage and current values measured in the same manner as described above when the product was new, the bearing The degree of wear and damage can be grasped. In addition, by determining whether the comparison difference with the new product is within the allowable range from the voltage and current values when the bearing is inspected and replaced, the bearing can be maintained until the end of its life. It can be fully used up.

Here, a comparison example of the voltage value and current value at the start of rotation of the submersible pump driving electric motor before and after bearing open inspection using the method according to this embodiment is as follows.

Before inspection After inspection 10.6V 8.8V 8.7A 7.4A As shown above, the voltage and current values are different before and after the bearing open inspection, so if these are used as judgment criteria, the above-mentioned It is possible to appropriately determine whether or not bearing open inspection or replacement is necessary. Incidentally, the above comparative example shows a case where the values after inspection are very close to the data when the product was new.

In the above example, the voltage and current values when the submersible electric motor M was confirmed to start rotating were compared with those of the new product, but it is not necessarily necessary to compare them with the voltage and current values of the new product. The voltage value and current value from the previous inspection may be compared as data to determine whether or not bearing open inspection and replacement are necessary.

〔Effect of the invention〕

As described above, when determining whether or not bearings of an electric motor need to be inspected or replaced, the present invention first changes the power supply voltage applied to the electric motor from zero V to the The voltage and current are gradually increased until the motor rotates, and when the motor starts rotating, the voltage and current values at that time are measured, and then the measured voltage and current values are compared with pre-prepared data to determine the difference. Whether or not the bearing needs to be opened and inspected or replaced is determined based on whether or not it is within the allowable range. Therefore, according to the present invention, it is possible to appropriately, simply and easily determine whether or not the bearing needs to be inspected or replaced, and it is also possible to discover abnormalities before the bearing inspection of the electric motor, and to prevent the bearing from being opened. This makes it easier to identify the presence or absence of bearings, and reduces the number of expensive bearing replacements, even if the motor is a submersible pump drive motor immersed in liquefied gas in a cargo tank on a deep-refrigerated ship. Therefore, it is possible to provide an economically advantageous electric motor bearing performance testing method that can save bearing costs and construction costs.

[Brief explanation of drawings]

The drawing is a circuit configuration diagram showing an embodiment for explaining the bearing performance testing method for an electric motor according to the present invention. 1...Power transformer, 2...No fuse breaker,
3... Electromagnetic switch, 4... Overcurrent relay, 5...
Variable transformer, 7... Voltmeter, 8... Ammeter, 9...
・Fuse, 10...Power indicator light, 11...Operation indicator light, SWI. SW2...stop, start switch. Applicant Sub-Agent Patent Attorney Takehiko Suzue II VW

Claims (1)

[Claims] When determining whether the bearings of the electric motor need to be inspected or replaced, first, the power supply voltage applied to the electric motor is reduced to zero V using a variable transformer installed in the power supply circuit of the electric motor.
The voltage and current values are gradually increased until the motor starts rotating, and when the motor starts rotating, the voltage and current values at that time are measured, and then the measured voltage and current values are compared with pre-prepared data, respectively. A bearing performance testing method for an electric motor, characterized in that whether the bearing requires open inspection or replacement is determined based on whether or not the difference is within an allowable range.