Using the KTA3 in group motor applications can reduce panel space as much as 60%.

Ideal for group motor installations:   The KTA3 can eliminate the need for larger and more expensive fuse blocks & fused disconnects, or circuit breakers. The potential cost savings in group motor installations 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 KTA3 line offers a wide application range from 0.1 to 25 FLA in installations up to 600V. For group motor applications, the KTA3 has a 1200A group installation rating, one of the highest in the industry.

Or as a manual starter: The KTA3 is also an excellent manual motor starter that employs all of the same motor protection features in one compact unit.

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 1/1000 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 KTA3 has a short-circuit capacity of up to 42kA at 600V.  Because each KTA3 is individually calibrated at the factory for the smallest and largest current, very accurate thermal overload protection is also obtained. In addition, the KTA3 is a Class 10 device . . . it trips within 10 seconds under a locked rotor condition (6 x FLA).

Other protection features: Single-phase protection is provided by the KTA3 at a maximum of 1.25 x FLA. Accurate adjustment of the overload trip ensures effective motor protection even with a phase loss.  Every KTA3 Motor Circuit Controller is also equipped with automatic ambient temperature compensation, which continually adjusts to surrounding temperatures. As a result, trip times remain constant.

Accessories add complete versatility: Whether in group motor installations or as a manual motor starter, numerous accessories are available that enhance the KTA3's performance. Auxiliary contact blocks, trip indicators, undervoltage, and shunt release modules snap onto the KTA3 without tools. The one pole auxiliary contact block is internally mounted, adding no extra dimension to the device. For group motor applications a compact bus bar system is available that speeds installation and provides an extremely clean and efficient panel.

The KTA3 In Group Motor Applications and the Canadian Electrical Code:

CEC 28-200 states that each motor must have a branch Circuit Protective Device (BCPD) consisting of a fused disconnect, fuse block, or circuit breaker.  Even though this method is highly effective, it has several drawbacks.

• Circuit breakers or fuse blocks for each branch motor circuit are expensive
• The panel space required to house these BCPDs is substantial.
• Installations of this type are labor intensive and therefore more costly.

Eliminate all but one BCPD

The next article of the code, however (28-206), provides several exceptions to 28-200 that allow you to connect a group of motors under one BCPD. These exceptions can be found under:

• 28-206(a) - 15A BCPD
• 28-206(b) - "The Smallest Motor is Protected"
• 28-206(c) - "Machine Tool or Woodworking Machines"

For example, Figure two above illustrates how a circuit would look using provisions (a) or (b) above.   What was once three branch circuits with three BCPD's becomes one branch circuit with one BCPD.

It appears that the exceptions in 28-206 take care of the expensive drawbacks to having one BCPD for each motor. The expensive fuses (or circuit breakers) have been eliminated. The panel space has been significantly reduced, and the labor it takes to install the circuit has been reduced.  Unfortunately, this solution raises a different set of problems.

• To service one motor, the power must be disconnected at the BCPD removing power to all of the other motors.
• The use gives up "close" individual protection against faults that are lower than the BCPD protection rating.
• Few overload relays have the "group installation" label required in 28-206(c).

KTA3:  The complete solution

By including the KTA3 Motor Circuit Controllers in the motor circuits as shown in Figure 3, the problems associated with 28-206 are solved:

• Elimination of all but one fuse block (or circuit breaker)
• Significant reduction of panel size
• Decreased wiring & installation time
• Individual disconnect for each motor is provided
• Assured protection against faults that are lower than the BCPD
• Product labeled for group installations

In addition to the cost savings and convenience of using the KTA3 in group motor applications, motor overload protection is enhanced.  Since the KTA3 is a Class 10 device, it offers optimum protection for today;s T-frame motors.  Also, the thermal overload element in each KTA3 is ambient temperature compensated and individually calibrated at the factory, further contributing to precise and reliable motor protection.

Overall, the KTA3 represents a level of quality and rigorous engineering that is unsurpassed in controlling and protecting your motor and motor circuit.

Single-phase protection is provided by the KTA3 at a maximum of 1.25x FLA.  Accurate adjustment of the overload trip ensures effective motor protection even with a phase loss.

Every KTA3 Motor Circuit Controller is also equipped with automatic ambient tempreature compensaiton, which continually adjusts to surrounding temperatures.  As a result, trip times remain constant.