Rerplacement Guide
DCS800-EP replaces the Reliance FlexPak® 3000

Replacement Guide - ABB DCS800-EP replaces the Reliance FlexPak 3000

Product Differences and Remedies

The DCS800-EP has been designed to match the form, fit, and function of the Reliance FlexPak 3000 in every way possible.
However, some differences still exist. This section identifies known differences and suggests remedies.


  1. Armature current rating
    Armature current variation between the two manufacturers does exist. The ABB drive current ratings are based on industry standard power ratings for DC motors.
    REMEDY: Select the proper DCS800 rating by ensuring the actual motor’s nominal current rating is less than or equal to the DCS800-EP armature current rating as shown in tables 1 & 2 above.
  2. Field current rating
    Variations in field current ratings also exist.
    REMEDY: Be sure the actual motor field current rating is less than or equal to the DCS800-EP field current rating as shown in tables 1 & 2 above.
  3. Field power supply type
    The FlexPak 3000’s internal field supply was voltage controlled.
    The DCS800-EP’s field supply is current controlled.
    Current control is superior to voltage control since field strength is proportional to current, not voltage. One benefit is that the DCS800-EP will automatically provide constant field strength whether the motor is cold or hot.
    REMEDY: None required but be prepared to enter the actual motor nominal field current rating, found on the motor nameplate, into the DCS800-EP during commissioning.
  4. Line Impedance
    Each DCS800-EP drive always requires a line reactor or transformer on the AC side of each drive. In some cases, the FlexPak 3000 did not require this.
    REMEDY: If a line reactor or transformer is already in use, it can be reused with the DCS800-EP. If not, drives 150 hp and below can be ordered with an internal line reactor (+E213) but be sure sufficient cabinet depth is available. An external reactor can also be used. See DCS800-EP Installation and Start Up Manual for dimensions and reactor recommendations.
  5. DC Contactor
    FlexPak 3000 drives 400 hp and above included a DC contactor.
    The DCS800-EP includes an AC contactor instead.
    REMEDY: Unless dynamic braking is also used, this should have no impact on system operation.
  6. Dynamic Braking
    The FlexPak 3000 had an option for dynamic braking. No option exists with the DCS800-EP.

    • Order the DCS800-EP without the AC contactor using plus code +0F250;
    • Reuse existing DC contactor (the DC contactor may need to be relocated off of the FlexPak 3000 panel) or purchase new EHDB contactor from ABB Controls and mount in a convenient location.
    • Reuse existing DB resistors.
    • Use DCS800-EP relay output “DO8” to control the DC contactor by wiring to terminal X96 (rated at 3A at 24Vdc or 115/230Vac).
    • Configure the drive for “US DC Contactor.” See: DCS800 Firmware Manual, sections:
      “Firmware Description: DC-contactor US version”
      “Firmware Description: Dynamic Braking.”
  1. Grounded vs. Isolated Inputs and Outputs
    The common of the digital inputs and outputs on the Flex-Pak 3000 were isolated from the rest of the drive but they are grounded on the DCS800-EP. This is only a problem on systems that have input/output wiring that runs from bay to bay or cabinet to cabinet or, for example, from the cabinet to a pushbutton pedestal on the machine. Systems with all I/O wiring completely inside a single cabinet bay should not have a problem.
    REMEDY: Add hardware to isolate the inputs and outputs such as the RDIO-01-KIT or 24Vdc relays (purchased from ABB controls).
Failure to add isolation when required as described above can cause damage to the DCS800 drive module!
  1. AC Tachometer
    When used with an optional AC Tachometer Feedback Kit (907KF0301), some FlexPak 3000 drives used an AC tachometer for speed feedback. The DCS800 is not compatible with AC tachometers.
    REMEDY: Use the DCS800 in “transducerless” mode by setting para. 50.03 = EMF, or replace the AC tachometer with a DC tachometer, 8 to 270 Vdc at maximum speed.
    NOTE: It may be possible to relocate and reuse the Reliance AC Tachometer Interface board. Consult with ABB or use a commercially available diode bridge.
  2. Disconnect handles
    DCS800-EP drives that include the optional circuit breaker use an ABB Tmax breaker. This type of breaker uses an optional Type RH through-the-door rotary operating mechanism.
    The operating mechanisms from the FlexPak3000 cannot be reused and the handle location will be different.
    REMEDY: Remove existing disconnect handle and cover up the holes. Install the ABB through-the-door operating mechanism Type RH in the appropriate location as shown in the DCS800-EP Installation and Start Up Manual.
  3. Inverting Circuit Breaker
    Inverting circuit breakers are standard on regenerative FlexPak 3000 drives from 400 to 600 hp (frames C & D).
    DCS800-EP drives use DC fuses instead.
    REMEDY: None required. The two are functionally equivalent.

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Specifications subject to change without notice.
DCS800-EP | Reliance FlexPak 3000 Replacement
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