DC Buyer's Guide

Application Information CD180AT-CD6900 Frames

Insulation Insulation life is dependent on many factors. Insulation failure results from either chemical or mechanical degradation or a combination of both. Chemical degradation is a function of the time and temperature at which the insulation is operated relative to its temperature rating. Roughly, a machine operated at the nominal temperature rating will operate twice as long as a machine operated 10°C higher. Chemical degradation can also be accelerated, if the machine operates in dirty or chemical atmospheres or in atmospheres of high moisture content . Mechanical degradation occurs when the conductors are subject to high forces. These forces may cause coil movement , which eventually can abrade the turn insulation on the wire or QaTPZ cWT Va^d]S X]bd[PcX^] Motor Heating Cooling air for dripproof fully guarded self-ventilated, and totally enclosed fan cooled direct current motors is provided by shaft-driven fans. At low operating speeds, the flow of ventilating air passing through the machine is reduced resulting in a decreased heat dissipation rate. Consequently, it becomes necessary to analyze the motor thermal capacities at each speed and load condition. In general, motors of dripproof fully guarded, self-ventilated, and totally enclosed fan cooled enclosures \dbc QT ^_TaPcTS PQ^eT % ^U cWT \^c^a QPbT b_TTS c^ ensure proper cooling.

Type of Motor

Maximum Monetary Overspeed

25 percent above the maximum nameplate speed or 15 percent above the corresponding no-load speed, whichever is greater. Not greater than 50 percent above full load base speed.

Shunt

Compound with speed regulation of 35 percent or less

Motor Pricing General Information

All DC motors may be subject to potentially dangerous overspeeding under certain conditions of misoperation. Overspeeding of a DC compound wound or shunt wound motor may occur if the shunt field circuit becomes de-energized. Unless the speed is inherently limited by the application of the motor, DC motors should be protected against dangerous overspeed by overspeed devices, field loss relays, or other means. Motors can overspeed due to improper wiring during X]bcP[[PcX^] 64 X]bcP[[PcX^] P]S X]bcadRcX^] Q^^Zb R^]cPX] statements and instructions to guard against such over- speed due to wrong initial connections. Specifications should require that guards be placed over exposed couplings, pulleys, pinions, and unused shaft extensions for the protection of the operating personnel. Care should be exercised in the selection of couplings, belts, ^a _X]X^]b fXcW SdT R^]bXSTaPcX^] VXeT] c^ bW^RZ [^PSb overloads, and pulley pitch diameters. See page 5.7 for bearing life and allowable shaft loading. Too small a pulley diameter will require excessive belt tension to prevent belt slippage. This, in turn, overloads the bearings and shafts which may result in bearing and/or shaft failure, and possible overspeeding of the motor. Additional coverage of the hazards in handling the rotating equipment covered in this publication may be found in the X]bcadRcX^] Q^^Zb bT]c ^dc fXcW cWT T`dX_\T]c Hazards Due To Environment Motors which operate in explosive atmospheres must meet the requirements of Articles 501-8 or 502-8 of the National Electrical Code. The Code assigns authority to approve the installation to “the authority having jurisdiction” (see Article € 3TUX]XcX^]b ^U cWT =42 Motors approved by U.L. for Class I, Group D or Class II, Groups E, F, and G are available in some ratings. However, it is the responsibility of the customer to be familiar with the NEC and the local jurisdictional requirements and to deter- mine that the motor selection (including possibly permissible alternatives to U.L. approved motors) is “acceptable to the authority having jurisdiction.”

Other Information Application Information Outline Dimensions Accessories and Modifications

Motor Enclosure Self-Ventilated Blower Ventilated

Standard Constant Torque

% ^U QPbT b_TTS

$ $ $

Separately Ventilated

TENV TEFC TEAO

% #

TEAAC TEWAC

$ $

Motors ventilated from a separate source are supplied with a constant flow of cooling air, which is independent of the motor operating speed. A constant supply of cooling air permits much lower speed operation of a separately ventilated motor at rated torque without exceeding a maximum allowable temperature rise. Continued operation at high temperature will significantly reduce insulation life. However, generally most applications have compensating periods of operation at some temperature lower than normal so that the use of the higher current for many applications is justified.

5.3

www.gemotorswolong.com GEP387-EN 07/19 Prices and data subject to change without notice.