Schneider Electric 58 TRX

Class 8839 58M Enclosed AC Drives

Specifications

182 09/2003

One disconnect shall be common to the

drive controller and bypass contactor.

2. Barriered bypass shall consist of

compartmentalized, multi-door enclosure

construction that provides electrica l

isolation of the AC Drive controller from the

bypass contactor using two OSHA and UL

approved disconnects. This configuration

shall remove all power to the drive

controller compartment when the drive

disconnect is in the open position. This

configuration shall allow provide maximum

user flexibility if servicing a drive while

remaining on bypass.

b. A TEST-NORMAL selector switch shall be

used with bypass to allow testing of the AC

Drive without running the motor. In the “Test”

position the isolation contactor shall remain

open preventing motor operation while

operating the AC drive.

c. The operator shall have full operational control

of the bypass starter using a door mounted

AFC/OFF/BYPASS selector switch.

d. Auto transfer to bypass function shall be

provided in the event of drive fault or failure.

This feature shall be enabled or disabled b y an

internally mounted selector switch. An

adjustable timer shall provide control of the

delay time between fault and transfer to

bypass.

2.16 HARMONIC MITIGATION EQUIPMENT

REQUIREMENTS

Note to Specifier: There are several solutions for

effective harmonic mitigation. The most common

approach is the use of a 5% line reactor. When

line reactors are properly sized for the drive

controller, the additional source impedance can

add provide effective levels of harmonic mitigat ion

for voltage distortion and attenuation of incoming

voltage transients. The alternate approaches

include the use of isolation transformers and

harmonic filters. The typical installation of

isolation transformers and filters are separately

mounted with proper branch circuit protection.

Filters require coordination with the AC Dri ve

power circuit and must not be part of the bypa ss

path. An alternate approach is the use of multi-

pulse drives, which are typically specified above

100 hp.

a. The AC Drive shall be provided with a 5%

rated line reactor mounted inside the

enclosure.

b. Th e AC Drive shall provide provisions and

terminations inside the drive enclosure for

branch circuit protection of a separately

mounted isolation transformer or harmonic

filter. The AC Drive disconnect shall serve as

disconnect for the harmonic filters. Branch

circuit protection shall be in accordance with

the NEC using fused protection. Harm on ic

filters shall be isolated from bypass path

operation if supplied.

2.17 HARMONIC ANALYSIS

Note to Specifier: Guidelines for voltage and

current distortion are addressed in IEEE Standard

519-1992 titled “IEEE Recommended Practices

and Requirements for Harmonic Control in

Electrical Power Systems”, which suggests

distortion limits dependent upon the electric

power distribution system for industrial and

commercial consumers. Collectively, all facility

loads and the building electrical distribution

network determines the harmonic levels at the

user & electric utility interface. The Electrical

Power Research Institute (EPRI) recognizes the

‘Point of Common Coupling’ or PCC as the

interface between user and electric utility (energy

meter) in the electrical distribution network. The

AC Drives manufacturer can provide calculations

through computer modeling, specific to the

installation, showing total harmonic voltage

distortion. Contractor to provide one line diagram

drawings to supplier including transformer

impedance. The AC Drive manufacturer needs

this information.

a. A harmonic distortion analysis shall be

performed and priced as a separate line item

by the AC Drive manufacturer based upon

documentation supplied by the contractor. The

documentation shall consist of one-line

diagrams, distribution transformer informatio n

(kVA, %Z, and X/R ratio) and emergency

standby generator performance

specifications. The harmonic distortion

analysis report shall be part of the approval

drawing process, submitted to the engineer for

approval.

b. If the calculations determine that harmonic

distortion values are higher than the voltage

and current values specified, the drive

manufacturer shall provide [line reactors,

isolation transformers, harmonic s uppressors]

to meet the intent of IEEE 519-1992

guidelines.