S200: Cables

See the Accessories page for a list of PNs and descriptions.

Long Cables

The DC resistance of long motor power cables steals some of the available voltage when motor current is high. As a result, there is a reduction in peak motor power so that acceleration and deceleration times can be longer. The cable resistance has no significant effect on lower speed torque or top speed. For most applications, the loss of performance is small with cables up to the maximum cable length specification.

WARNING: Do not operate an S200 DC Input Drive with long cables at the lower end of the bus voltage range, because too much of the available voltage is stolen by the cable resistance.

For S200 AC Input Drives, the DC resistance of the motor power cable is rarely an issue because the voltage drop across the resistance is usually a small fraction of the available nominal bus voltage.

For S200 DC Input Drives with long cables and demanding dynamics, the 14 AWG cable is preferred over the 18 AWG cable. Cable voltage drop vs. cable length is shown in the table below.

Cable Voltage Loss vs. Cable Length

Cable Length (meter)	2 x Rphase (ohm)	V line-line peak at 0.866 x 18 A rms 18 AWG cable	V_LOSS in cable as a percent of 75 Vbus
Cable Length (meter)	2 x Rphase (ohm)	V line-line peak at 0.866 x 18 A rms 18 AWG cable	18 cable	14 cable
3	0.126	2.77	3.7%	1.5%
10	0.413	9.09	12.1%	4.8%
25	1.03	22.7	30.3%	12.0%
20	(50 m not recommended with 6/18 A rms)		N/A	24.0%

Custom Composite Cables

A composite cable has both feedback and power wires in one cable. One of the critical requirements for a composite cable is to provide a high degree of isolation between the power and feedback wires. For 240 VAC-connected drives, the power wires can have up to 400 Vpeak-peak fast switching PWM waveforms that can couple to the feedback wiring, causing communication errors between the Drive and the Smart Feedback Device (SFD).

Kollmorgen has developed and sells a composite cable that has very good isolation between the power and feedback sections. It is strongly recommended that this raw cable be used for custom composite cable designs. Contact your Kollmorgen sales representative for additional information. (PN: )

If this cable does not meet your specifications, the following are some guidelines for custom composite cable development. Due to the complexity of modeling and understanding cable coupling, a new composite cable needs to be prototyped and tested to have confidence that it will be reliable.

Composite cable should have double concentric feedback shields – one shield within another.
The raw composite cable that has been tested and is known to work well with the S200 has the following structure: double, concentric shields around the feedback wires, plus an outer shield around the whole cable (see diagram below). This type of raw cable is strongly recommended. Testing shows double concentric shielding is ten times better than single shielding at reducing coupling from the power wires to the feedback data wires.

Composite Cable Cross-Section

There can be substantial capacitance between the power wires and adjacent feedback shield in a composite cable. Some of the PWM ampere level spikes tend to return in this adjacent shield, affecting the power stage voltage and current drive the feedback shield nearest to the power wires. In a single-shielded feedback cable this driven shield is also around the feedback data wires, so some coupling can occur. With double, concentric feedback shields, the driven shield is the outer of the two feedback shields, and interposed between the driven shield and feedback data wires is the inner feedback shield. Typically, the inner feedback shield is isolated from the connector shells and is connected to the return for the power supply powering the feedback device.

NOTE: A raw cable with two pairs of twisted, shielded feedback sections inside a composite cable is electrically the same as single feedback shielding. There may physically be two feedback shields in such a cable, but these shields are not concentric. There is only one shield between the power and feedback wires. Whereas the double, concentric feedback shields have two shields between the power and feedback wires.

SFD +5 and Gnd Resistance Spec
To ensure that the SFD +5 V at the SFD inside the motor is within specification, the voltage drop total in the SFD +5 V wire and SFD +5 V RTN wire must not be greater than 0.5 V at 150 mA. For this reason, a cable requirement is that the total resistance of the feedback SFD +5 V wire plus SFD +5 V RTN wire must be < 3.33 Ω (at 20° C). In practice, this means that for long cables, the AWG wire gage needs to be considered.

NOTE: The inner shield of the a double, concentric feedback cable, when isolated from the terminating connector shells, can also function as a conductor to carry some or all of the SFD +5 V RTN current. This is useful for keeping the total SFD +5 and RTN resistance within specification on long cables without having large diameters.

Feedback Characteristic Impedance
Kollmorgen's S200 feedback cables are designed to have a feedback data pair differential impedance of 81 Ω (at 1 MHz). Impedances in the range of 50 to 100 Ω, while not tested, will likely work properly with the S200 drive.

Two suggestions simplify the design of customer composite cable:

Purchase the raw composite cable from Kollmorgen. The cable has good shielding properties.
Purchase a composite feedback cable built by Kollmorgen. Review its construction, and test its performance. There are many ways to connect the multiple shields of a composite cable. A good way to understand how the Kollmorgen composite cable is built is to buy a short Kollmorgen S200 composite cable, open it up, and see how the shields at both the motor and drive end are connected.

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