Medium-Voltage Switchgear and Circuit Breakers:DC Battery Trip

DC Battery Trip

The battery is probably the most reliable source of control power when it is properly maintained and serviced. It uses single contact protective relays to energize the breaker trip coil. It is unaffected by voltages and current during fault conditions. Generally, a 125 or 250 V battery is recommended for MV switchgear when both closing and tripping is required. When such is not available, a 48 V battery may be used for tripping only. However, it must be sized to meet the required load of the switchgear. A battery trip circuit is shown in Figure 7.30a. Long service can be obtained from batteries when they are serviced regularly, fully charged, and the electrolyte level maintained at the proper level.

Capacitor Trip

The capacitor trip device is commonly used where a DC battery source is not available or uneconomical, such as in outdoor switchgear or where only few circuit breakers are installed. The capacitor device simply consists of a capacitor and half-wave rectifier charged from an AC control power trans- former. When using a capacitor trip device, a separate capacitor trip unit is required for each breaker.

Medium-Voltage Switchgear and Circuit Breakers-0269

The capacitor trip device comes in two types: nonautocharge and autocharge. The nonautocharge retains adequate charge for a short time (about 30 s) after the AC supply is lost. The autocharge consists of a regulated charge. It con- tains a voltage amplifier, a battery, and a battery charger. In case of loss of AC supply, the voltage amplifier steps up the battery voltage to maintain an adequate charge of the capacitor for several days. The simple capacitor trip device circuit is shown in Figure 7.30b.

Incoming search terms:

Related posts:

Reference Data and Tables
Facility Wiring and Transient Protection:Power-System Protection
Power System Protection Methods:Assessing the Lightning Hazard
Power Transformers:Inductive Properties.
Medium-Voltage Switchgear and Circuit Breakers:Electrical Switchgear Testing
Electrical Power System Grounding and Ground Resistance Measurements:Selection of Grounding Method
Overhead Lines:Conductor Data
Overhead Lines:Line Impedance Tables
Another Groups of Thermal Optimized Modulation Methods of Three-Level Neutral-Point-Clamped Inverter...
General Overview:Fossil Fuel Reserves
General Overview:Access to Modern Energy
The Current Situation and Perspectives on the Use of Solar Energy for Electricity Generation:Austria

Leave a comment

Your email address will not be published. Required fields are marked *