Panamax M5510-PRO Owner's Manual - Isolated Vs. Balanced Power
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ISOLATED vs. BALANCED POWER
Supply
Equipment
LINE
NEUTRAL
GROUND
LINE
NEUTRAL
GROUND
Supply
Equipment
LINE
NEUTRAL
GROUND
LINE
NEUTRAL
GROUND
Power Modes in the MAX
®
5510
Single-phase grounded-neutral power
The standard method of residential power delivery in the U.S.
The neutral, or "grounded" conductor, is bonded to the earth, or
"grounding" conductor. The N-G panel bond creates a severe
imbalance with respect to common-mode currents, which can
lead to "hum" in A/V equipment. There are three problems with
this configuration that are specifically targeted by our "Isolated"
and "Balanced" power modes:
1. Line and neutral current imbalance. Unbalanced currents in
the L-N can radiate magnetic fields, which can couple inductively
from connected power cords to nearby A/V cables.
2. Ground skew. Voltage drops due to common-mode current
flowing into the earth ground can cause a skew between signal
ground references in interconnected A/V equipment.
3. Line and neutral voltage imbalance. Unbalanced voltages
from line and neutral to ground can cause connected power
cords to radiate electrical fields, which can couple capacitively to
nearby A/V cables.
With "Isolated Power" the N-G panel bond is broken by floating
the line and neutral, and the ground reference voltage is driven to
neutralize the hum-producing ground leakage currents (2).
Consequently, L-N currents are equalized, effectively eliminating
magnetic field radiation from connected power cords through
current phase cancellation (1). Radiated electrical fields can still
be evident (but to a much lesser degree than with grounded-neu-
tral power), unless the impedances from L-G and N-G in the
connected equipment are equal.
With "Balanced Power", the asymmetric, zero-volt N-G reference
at the panel is replaced by a symmetric ground reference
between line and neutral. Hum-producing common-mode
currents (2) and radiated electrostatic fields in the connected
power cords (3) are both eliminated by voltage phase cancella-
tion. Radiated magnetic fields can still be evident (but to a much
lesser degree than with grounded-neutral power), unless the
impedances from L-G and N-G in the connected equipment are
equal.
Conclusion
"Balanced" and "Isolated" Power are both exceedingly efficient
at overcoming the inherent problems of the unbalanced earth
ground reference in domestic single-phase power systems,
with small but definable distinctions. They are both effective in
reducing common mode currents and radiated magnetic and
electrostatic fields from connected power cords. The primary
difference is simple: "Isolated Power" is better at reducing the
magnetic (inductive) component, and "Balanced Power" is better
at reducing the electrical (capacitive) component. Because all
A/V cables have some amount of inductance and capacitance
(defined collectively as "impedance"), they are susceptible to
both types of interference, and the trade-offs will vary with
the system configurations.
Isolated Power
Balanced Power