Instruction Manual

Rockwell Automation Publication 1769-UM006E-EN-P - July 2013 63
Installation and Wiring Chapter 3
Transistor Output Transient Pulses
The maximum duration of the transient pulse occurs when minimum load is
connected to the output. However, for most applications, the energy of the
transient pulse is not sufficient to energize the load.
Figure 17 illustrates that the duration of the transient is proportional to the load
current. Therefore, as the on-state load current increases, the transient pulse
decreases. Power-up transients do not exceed the time duration shown below, for
the amount of loading indicated, at 60 °C (140 °F).
Figure 17 - Transient Pulse Duration as a Function of Load Current
ATTENTION: A transient pulse occurs in transistor outputs when the
external DC supply voltage is applied to the output common terminals (for
example, via the master control relay). The sudden application of voltage
creates this transient pulse. This condition is inherent in transistor
outputs and is common to solid state devices. A transient pulse can occur
regardless of the controller having power. Refer to your controller’s user
manual to reduce inadvertent operation.
0.4
1.0
0.9
0.8
0.7
0.6
0.5
0.3
0.2
0.1
0.0
10009008007006005004003002001001
On-State Load Current (mA)
Time - Duration of Transient Pulse (ms)