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MCBs technical details
Definitions according to standards for miniature circuit breakers

Rated operational voltage (Ue) UL 1077
The rated operational voltage of an equipment is a value of These requirements apply to supplementary protectors
voltage which, combined with a rated operational current, intended for use as overcurrent, or over- or under-voltage
determines the application of the equipment and to which the protection within an appliance or other electrical equipment
relevant tests and the utilization categories are referred. For where branch circuit overcurrent protection is already
single-pole equipment it is generally stated as the voltage provided, or is not required.
across the pole. For multi pole equipment it is generally stated Compliance with this standard is acceptable for use as
as the voltage between phases. a component of an end product.
An equipment my be assigned a number of combinations of
rated operational voltage and associated making and
breaking capacities for different duties and utilization
categories.

Max. power frequency recovery voltage (Umax)
Voltage which appears across the terminals of a pole
of a switching device after the breaking of the current.

For all breaking capacities and short-circuit breaking
capacity tests, the value of the power-frequency recovery
voltage shall be 105 % of the value of the rated operational
voltage. This value shall be within the specified tolerance
(voltage 0 / + 5%).

NOTE:
The value of 1.05 times the rated operational voltage for the power
frequency recovery voltage, together with the test voltage tolerance resulting in
a maximum voltage of 1.1 times the rated operational voltage, is deemed to cover
the effects of variations of the system voltage under normal service conditions.

UL 489
The requirements of this standard cover molded-case circuit
breakers, circuit breaker and ground-fault circuit-interrupters,
fused circuit breakers, and accessory high-fault protectors.
These circuit breakers are specifically intended to provide
service entrance, feeder, and branch circuit protection in
accordance with the National Installation Codes in Annex B,
Ref. No.1.
This standard also covers instantaneous-trip circuit breakers
(circuit interrupters) specifically intended for use as part of
a combination motor controller in accordance with the
National Installation Codes in Annex B, Ref. No. 1.
UL489B
These requirements cover molded-case circuit breakers,
molded-case switches, and circuit-breaker enclosures rated
up to 1000 V dc, intended for use with photovoltaic (PV)
systems and Article 690 of the National Electrical Code,
ANSI/NFPA-70. These requirements are intended to be used
in conjunction with the requirements in the Standard for
Molded-Case Circuit Breakers, Molded-Case Switches and
Circuit-Breaker Enclosures, UL 489.