6Model 2600XM Controller Installation Guide
Connecting AC Power
The Model 2600 M contains an internal power supply which provides two mutually-
isolated voltages (+5 VDC and +24 VDC) for the operation of the controller. Also
included are two LED indicators for these voltages and a power ON-OFF switch.
The controllers power supply requires AC power, either 120 VDC or 240 VAC nominal
for proper operation. Power is applied to the controller via the standard IEC-type power
connector on the side of the controller. A US-standard three-prong power cord is pro-
vided with the controller for this purpose.
The supply voltage required is determined by a voltage selector on the side of the unit
(see diagram below). A fuse of the appropriate rating must also be installed in the fuse
holder on the front of the controller.
Voltage Range Fuse
120 VAC 90-132 1 Amp
240 VAC 190-264 1/2 Amp
Using Step-down or Isolation Transformers
When using a step-down or isolation transformer to supply power to the controller, be
aware of the following potential issues, all of which are drawn from experience:
Step-down transformers are typically derive 120 VAC from much higher voltage
lines that are also being used to power heavy equipment. Often, when motors are
first energized in heavy equipment, the stall currents that result can cause the voltage
supplied to the step-down transformer to drop by as much as 50%. Because step-
down transformers are ratio-metric devices, the voltage supplied to the controller
drops proportionately, causing a potential system malfunction.
The relatively light load imposed by the controller on the transformer secondary may
result in excessive voltage being present, representing a potential hazard to the
system.
Neither type of transformer represents ideal protection against electrical noise.
Inter-winding capacitances can result in noise transference among windings, and
differential noise may still be electromagnetically coupled to the secondary.
Adequate grounding of the controller is still critical to its proper performance. For
more information, see the section on The Importance of Proper Grounding.
These issues often point to the use of an independent power feed (120 or 240 VAC) for
the controller and associated components. The resulting additional stability and design
integrity are often well worth the slight additional cost.
The Importance of Proper Grounding
The controller is outfitted with an integral line filter to protect against electrical noise
carried on the AC power line. This line filter, along with the shielding provided by the
controller enclosure itself, depend on the presence of a good ground connection for
effectiveness. This is normally accomplished by connecting the controllers power cord
to a well-grounded outlet.
As with any electronic equipment, the controllers ground should follow a direct, low-
impedance path to the plants power source. If possible, this path should not be shared
by any machinery which injects a large amount of electrical noise into the ground.
In instances where step-down or isolation transformers are being used to power the
controller, the ground connection should still be made directly to the controller.
For further consideration regarding noise protection, refer to the Application Note,
Reducing Noise Susceptibility. Application notes may be obtained at no charge from
your distributor or directly from CTC.
Model 2600XM Power Connections
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