CBEMA CURVE

In 1977 the Computer and Business Equipment Manufacturers Association provided an energy performance profile for computer equipment known as the CBEMA curve. Revised by the Information Technology Industry Council (ITIC) in 1996 it will continue to be referred to as the "CBEMA Curve". A necessary tool in determining the immunity limits in modern office electronic equipment. Voltage levels and durations at the equipment terminals, within the tolerance envelope, represent acceptable energy being delivered.

LET THROUGH VOLTAGE” SEEN BY PROTECTED EQUIPMENT

The Problem:

To achieve the best possible surge protection for facility, it is essential that incoming surge currents be provided with a direct very low impedance pathway to earth ground.
Large incoming surge currents will cause high "let through" transient voltages to appear across sensitive downstream equipment.
The diagram below shows surge voltage drops that appear on the protector's cabling to the service panel as well as those that appear on the protector's internal wiring.

The Solution:
MCG has coordinated the protector design and its related wiring. We call it the "Micro-Z" solution.
Employing a two-step approach, MCG has significantly reduced the let through voltage that appears across a surge protector and its related cabling.
1. The internal impedance within the protector is reduced as result of close attention to its physical layout. To this end, MCG's patented design approach creates short direct pathways with canceling electromagnetic fields.
MCG's protectors are especially designed to be exceedingly compact. (Physically large protectors have large internal impedances).
MCG's breakthrough Micro-Z cable approach forces electromagnetic field cancellation along the entire cable length.
The chart below dramatically illustrates the improved performance of the Micro-Z cable compared to conventional cabling.

David Pérez Rolando
Electrical Engineer