Eaton Cutler-Hammer AF91 Operation And Service Manual

AF91 EXTERNAL DYNAMIC BRAKE KITOPERATI0N and SERVICE MANUALINTRODUCTIONThe Dynamic Brake kit consists of a compact externally mounted dynamic brake module that monitors the DC bus voltageand AC line voltage of a variable frequency drive. The theoretical DC bus voltage should never exceed 1.414 times the ACline voltage. Should the DC bus voltage exceed this value, the dynamic brake module will bleed energy off of the DC bus byplacing a resistor across the bus at a variable duty cycle. As the DC bus level increases above the threshold level, the widthof the pulses increases to bleed more energy per second off of the DC bus. As the AC line voltage changes, the dynamicbrake module threshold level will automatically change to keep the threshold level at 1.41 times 1.1 times the AC line voltage.WARNING: Do not service equipment with either AC and/or DC voltage applied. Unit can be the source of fatal electricalshocks! To avoid shock hazard, disconnect AC and DC power and allow DC bus to decay completely before working oncontroller. Warning labels (not supplied) must be attached to terminals, enclosure and control panel.INSTALLATIONProper location of the dynamic brake unit is necessary to achieve specified performance and normal lifetime operation. Thedynamic brake unit should always be installed in an area where the following conditions exist.• Ambient operating temperature.Enclosed Unit: -10 to 40°CChassis Unit: -10 to 50°C• Protected from rain and moisture.• Shielded from direct sunshine.• Free from metallic particles and corrosive gas.• Free from oil, grease and liquid.• Free from massive vibration.• Free from high electromagnetic radiation.• Free from radioactive material.• Free from flammable material.• Installation of the dynamic brake unit must be oriented so that the front side of the unit faces front and the top of the unit isdirected upward for maximum heat dissipation.• Mounting of the dynamic brake unit must be to a non-combustible panel.Note: The heatsink may heat up to above 100°C during maximum braking. Warning labels (not included) should beinstalled warning personnel of the high temperature of the heatsink.

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