MANUAL MOTOR STARTERS
KT4 Manual Starting from 1/2 to 10 HP
The KT4 is a manual motor starter that employs the features of power switching, thermal overload protection and control circuit signaling in one compact unit. This manual motor starter has the advantage of a high speed magnetic trip mechanism which limits the let-through current under short-circuit conditions. The KT4 can be supplied with field-installable shunt trip or an under voltage trip unit which exceeds the capabilities of the classic manual motor starter. This manual motor starter is available in a general purpose and a watertight enclosure. For an explosion proof application, we recommend the KTA7 Controller used in its Manual Starter mode.
Circuit Protection in Half the Space
The KT4 can eliminate the need for larger and more expensive fuse blocks, fused disconnects, or circuit breakers. The potential cost savings in group motor installations, according NEC 430-53c, can be as much as 35% over conventional methods of branch circuit protection. And, because so many features are combined into one small unit, panel space can be slashed by as much as 60%.
In addition, the KT4 line offers a wide application range from 0.1 to 16 FLA in installations up to 600V. For group motor applications, the KT4 series has a 250A group installation rating, with a withstand rating as high as 42 KAIC.
Excellent short circuit and thermal overload protection
In the event of a short-circuit, the contacts are opened by magnetic, non-adjusting tripping elements in times approaching 2/1000 of a second. This results in the extremely rapid build-up of an arc voltage which limits the current of the short-circuit to a very low level. Because of this superb current limiting capability, the let-through current is significantly reduced and the potential for damage is limited.
Because each KT4 is individually calibrated at the factory for the smallest and largest current, very accurate thermal overload protection is also obtained. In addition, the KT4 is a Class 10 device — it trips within 10 seconds under a locked rotor condition (6 x FLA). Every KT4 Manual Motor Starter is equipped with automatic ambient temperature compensation, which continually adjusts to surrounding temperatures. As a result, trip times remain constant and accurate.
Accessories add versatility
Whether in group motor installations or as a manual motor starter, numerous field-installable accessories are available to enhance the KT4’s performance:
- Auxiliary contact blocks — are available for internal or external mounting, providing signal switching capability for control circuits.
- Shunt trip and under-voltage release modules — provides the ability to remotely actuate the KT4 in emergency situations or continuously monitor the line voltage.
- Enclosures — are available in general protection (IP41) and watertight (IP55), complete with lockable accessories.
- Compact bus bar system — reduces the task of line side wiring in multiple motor starter installations which reduces the labor cost of installation.