ABB capacitor duty contactor

UA30..RA 3-pole contactors for capacitor switching can be used in installations in which the peak current far exceeds 100 times nominal rms current. The contactors are delivered complete with their damping resistors and must be used without additional inductances. The capacitors must be discharged (maximum residual voltage at terminals ≤ 50 V) before being re-energised when the contactors are making. Their electrical durability is 2,50,000 operating cycles for Ue< 500 V and 1,00,000 operating cycles for 500 V ≤ Ue ≤ 690 V. The UA..RA contactors are fitted with a special front mounted block, which ensures the serial insertion of 3 damping resistors into the circuit to limit the current peak on energisation of the capacitor bank. Their connection also ensures capacitor pre-charging in order to limit the second current peak occurring upon making of the main poles. The insertion of resistors allows to dampen the highest current peak of the capacitor when switching on, whatever its level. The UA..RA series 3-pole contactors are of the block type design.

Main poles and auxiliary contacts: Three main poles, one built-in auxiliary contact
Control circuit: AC operated with laminated magnet circuit
Accessories: A wide range of accessories is available.

Capacitor transient conditions
In low-voltage industrial installations, capacitors are mainly used for reactive energy correction (raising the power factor). When these capacitors are energised, over-currents of high amplitude and high frequencies (3-15 kHz) occur during the transient period (1-2 ms). The amplitude of these current peaks, also known as “in rush current peaks”, depends on the following factors:

• The network inductances
• The transformer power and short-circuit voltage
• The type of power factor correction

Application
The UA..RA contactors can be used in installations in which the peak current far exceeds 100 times nominal rms current. The contactors are delivered complete with their damping resistors and must be used without additional inductances.

For more information, visit:
R.SANGHAVI MERCANTILE PVT. LTD.
Website: www.abbdealer.com