Specifications

2–27
Principles of Operation
Hammer Bank Cooling
The hammer driver board also powers a blower fan that cools the hammer
bank. A fixed 60/40 signal (PWM) is provided to the hammer driver board to
run the blower fan. The hammer driver board demodulates this signal to a
binary (on/off) logic signal, then drives a MOSFET that powers the blower.
A current monitoring circuit tells the RTPU when the blower is running. If
the blower is stalled or not connected, the RTPU declares a fault. (See
Figure 2–17.)
Blower
Running
Blower
Fault
48 V
Blower +
Blower –
Demodulator
Bank Fan
PWM
Figure 2–17. Hammer Bank Cooling