Rockwell Automation RELIANCE ELECTRIC SP500 - 4.3 Installing External Components

4.3
4.3.1
4.3.2
4.3.3
Installing External Components
Install the input power and output power components that are located outside of the
SP500 enclosure. See figure 5.1. The following sections describe disconnect,
transformer, and AC line branch protection installation.
Disconnects
An input disconnect (for example, a switch or circuit breaker) must be installed in the
line before the drive input terminals in accordance with local, national, and
international codes (e.g., NEC/CEC). Size the disconnect according to the inrush
current as well as any additional loads the disconnect might supply. Coordinate the
trip rating for the current (10 to 12 times the full load current) with that of the input
isolation transformer, if used. Refer to section 4.3.3 for additional information.
Input AC Line Branch Protection
ATTENTION: Most codes require that upstream branch protection be
provided to protect input power wiring.
User-supplied branch circuit protection fuses must be installed according to the
applicable local, national, and international codes (for example, NEC/CEC). The fuses
must be installed in the line before the drive’s AC input terminals. Table 3.9 provides
fuse values.
Transformers
ATTENTION: Distribution capacity above the maximum recommended
system KVA rating (100 KVA for 115/230 VAC, 1000 KVA for
460/575 VAC) requires the use of an isolation transformer, a line reactor,
or other means of adding similar impedance to the drive’s input power
wiring.
ATTENTION: When the AC line is shared directly with other SCR-
rectified drives, an optional snubber resistor braking kit might be required
to alleviate excess DC bus voltage
Input isolation transformers may be needed to help eliminate the following:
* Damaging line voltage transients.
* Line noise from the drive back to the incoming power source.
* Damaging currents that could develop if a point inside the drive becomes grounded.
Observe the following guidelines when installing an isolation transformer:
* A power disconnecting device must be installed between the power line and the
primary of the transformer. If the power disconnecting device is a circuit breaker, the
circuit breaker trip rating must be coordinated with the inrush current (10 to 12 times
the full load current) of the transformer.
4-6 SP500 AC Drive Installation and Operation Manual Version 3.1