RESISTORS

RC Filters

Low-inductance resistor-capacitor filter systems protecting medium-voltage machines and equipment against fast transient overvoltages.

RESISTOR-CAPACITOR / TRANSIENT FILTERING

FAST TRANSIENT
EVENT → RC FILTER
NETWORK → MV EQUIPMENT
PROTECTION

Conceptual protective function; exact RC values must be engineered.

TECHNICAL OVERVIEW

Purpose and operating principle.

LMZ RC filters combine low-inductance resistors and capacitors and are connected in parallel between the protected equipment and switchgear. They are used to reduce fast transient voltage stress on insulation in MV motors, generators, dry-type transformers and shunt reactors.

KEY FEATURES

Application-driven characteristics and selection criteria.

Helps extend insulation lifetime by reducing fast transient overvoltage stress.

Protects insulation between windings of motors, generators and transformers.

Helps protect against high-frequency overvoltages caused by reignitions across vacuum circuit-breaker or switchgear contacts.

Protects equipment against high-frequency overvoltages associated with arc-furnace applications.

Typical applications include large motors, generators, induction/arc furnaces, shunt reactors and dry-type transformers.

An earth-fault relay can be included for arc-furnace applications where required.

RESISTOR SYSTEMS

Electrical and thermal duty define the final resistor configuration.

LMZ resistor systems are selected around the network, current, voltage, thermal duty, operating cycle and environmental requirements of the application.

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