API STD 546
Brushless Synchronous Machines - 500 kVA and Larger
|Publication Date:||1 June 1997|
1.1.1 This standard covers the minimum requirements for form-wound and bar-wound brushless synchronous machines in petroleum related industry service. This standard includes synchronous motors and generators with two different rotor designs:
a. The conventional salient-pole rotor with solid or laminated poles.
b. The cylindrical rotor with solid or laminated construction.
Note 1: A round bullet (•) at the beginning of a paragraph indicates that either a decision is required or further information is to be provided by the purchaser. This information should be indicated on the data sheets (see Appendix A); otherwise it should be stated in the quotation request or in the order.
Note 2: A square bullet (▪) at the beginning of the paragraph indicates additional requirements for special-purpose machines are: motors that drive high-inertia loads, vertical machines that support high-thrust loads, part of a complete train requiring vibration sensitivity criteria, operate in abnormally hostile environments, or are critical unspared equipment.
Note 3: This standard may be applied to adjustable speed motors with appropriate attention to the specific requirements of such applications. For adjustable speed applications, proper selection of the motor and drive is required to avoid the following conditions:
a. Motor rms current exceeding the continuous sinusoidal nameplate rating due to excessive voltage harmonics or improper volts/hertz levels.
b. Excessive winding temperature due to insufficient cooling, excessive torque levels, improper volts/hertz levels and increased losses due to harmonics.
c. Insufficient motor accelerating torque at reduced speeds due to insufficient volts/hertz levels or limitations in the drive's momentary current capacity and excitation system.
d. Increased sound levels due to increased fan speed, excitation of mechanical resonances, and/or magnetic noise caused by supply source harmonics.
e. Mechanical failure of the motor or coupling due to torque pulsations, operation at or near mechanical resonances, or excess speed.
f. Winding failures due to repetitive high amplitude voltage spikes created by the drive system.
g. Motor ground insulation overstress due to increased common mode voltage.
h. Damage to the motor and drive due to improper application of system capacitance.
i. Higher motor temperatures which may limit application in Division 2 classified locations.
j. Shaft voltages/currents due to harmonics which may cause bearing failure.
k. Possible resonance with, and overheating of, surge capacitors (surge capacitors are not recommended).
l. Rotor heating due to drive-created space harmonic mmf (e.g. 6th, 12th, etc. harmonic rotor currents).
Note 4: [ESP] designates use of an electrical standard paragraph. [MSP] designates the use of a mechanical standard paragraph.
1.1.2 When the machine is specified as special purpose on the Purchaser's Synchronous Machine Data Sheets (Appendix A), the paragraphs that are marked with square bullets (▪) shall also apply. Where a paragraph includes both a round and square bullet, that paragraph shall apply when the machine is specified as special purpose, or when indicated on the data sheets if the machine has not been specified as special purpose in the purchase order.
1.1.3 This standard requires the purchaser to specify certain details and features. In order for this standard to be meaningful as an aid to procurement, the purchaser must complete the data sheets in Appendix A or B. [ESP]