Baldor MN1274 06/2001 Input power conditioning, Power disconnect and protection devices

Ungrounded distribution systems

To avoid equipment damage an isolation transformer with a grounded secondary is recommended. This provides three phase AC power that is symmetrical with respect to ground.

2.3.2Input power conditioning

Baldor drives are designed for direct connection to standard single and three phase lines that are electrically symmetrical with respect to ground. Certain power line conditions must be avoided; an AC line reactor, an isolation transformer or a step up/step down transformer may be required for some power conditions.

HIf the feeder or branch circuit that provides power to the MintDrive has permanently connected power factor correction capacitors, an input AC line reactor or an isolation transformer must be connected between the power factor correction capacitors and the MintDrive.

HIf the feeder or branch circuit that provides power to the MintDrive has power factor correction capacitors that are switched on line and off line, the capacitors must not be switched while the drive is connected to the AC power line. If the capacitors are switched on line while the drive is still connected to the AC power line, additional protection is required. A Transient Voltage Surge Suppressor (TVSS) of the proper rating must be installed between the AC line reactor (or isolation transformer) and the AC input to the MintDrive.

2.3.3Power disconnect and protection devices

Apower disconnect should be installed between the input power service and the MintDrive for a

fail-safe method to disconnect power. The MintDrive will remain in a powered condition until all input power is removed from the drive and the internal bus voltage has depleted.

The MintDrive must have a suitable input power protection device installed. Recommended circuit breakers are thermal magnetic devices (1 or 3 phase as required) with characteristics suitable for heavy inductive loads (D-type trip characteristic). Recommended time delay fuses are Buss FRN on 230VAC or equivalent, following the UL 508C recommendation of a fuse size of four times the continuous output current of the drive. Dual element, time delay fuses should be used to avoid nuisance trips due to inrush current when power is first applied.

For CE installations the Gould Shawmut Cat. No. ATMR15 may be suitable, up to 15A.

LN

Earth

Circuit

Breaker

L N

MintDrive

L N

Fuse

Connection

L N

Circuit breaker and fuse not supplied. For CE Compliance, see Appendix C.

Figure 4 - Circuit breaker and fuse, single phase, package size A or B

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