TM 10-5410-228-24
1.15 ELECTRICAL SYSTEM.
Refer to the CBPS system schematic Figure 1-8 and troubleshooting schematic in Appendix F when reading
CBPS electrical theory of operation.
1.15.1 General Information.
The CBPS uses three main voltages for operation. 208 VAC, three phase is used to operate the electric
heaters. The 208 VAC, three phase is available only when supplied by the TQG, external power source.
Therefore the electric heaters may only be used when the TQG external power source is available. 115 VAC,
single phase is used to power the outlet receptacle on the back of the LMS. This provides power for ABS
lighting, portable recirculation fans, and medical or other miscellaneous equipment requiring 115 VAC,
single phase. The main power requirement for the CBPS is +24 VDC. It is used to power the circuitry used
to control the hydraulic functions and additional lighting.
The 24 VDC is distributed throughout the CBPS system from the 24 VDC bus through four main circuit
breakers located on the front of the Rear Control Panel:
HEAT/COOL circuit breaker A4CB1.
NBC/VENT circuit breaker A4CB2.
INSTM/CONT circuit breaker A4CB3.
LTG/INTERCOM circuit breaker A4CB4.
NOTE
The components serviced by circuit breakers A4CB1 through A4CB4 are the same whether
using ECV (internal power) or 10KW TQG (external power).
These circuit breakers protect the electrical circuits to which they distribute 24 VDC. All four of the circuit
breakers must be turned on (closed) for complete CBPS electrical system operation.
When setting the CBPS for static mode, position vehicle shifter to PARK or NEUTRAL, and set parking
brake. The ECV engine will start with shifter in either PARK or NEUTRAL. PARK is preferred. After ECV
engine is running and engine RPM has stabilized, set EPG switch on vehicle control box to ON position. It
could take several minutes for engine RPM to stabilize, especially in cold weather.
NOTE
Do not set EPG switch on vehicle control box to "ON" before starting ECV engine. Proper
starting procedure is to start ECV engine and let engine rpm stabilize prior to setting EPG
switch to "ON".
+24 VDC is applied from vehicle wire 29D, through closed contacts of vehicle neutral switch, to pins X1 and
X2 of relay A8K2. With A8K2 energized, setting start/stop switch to start (S) position, applies +24 VDC to
starter motor. When engine starts and start/stop switch is released, it automatically returns to run (R)
position. +24 VDC is also applied to diode A17D2.
Diode A17D2 conducts, energizing relay A17K1. +24 VDC from the battery pack is applied across closed
contacts A1 and A2 of A17K1 to line A (hot). Ground (common) is applied to line B. +24 VDC from ECV
battery pack is also applied to EPG circuit breaker A8CB1. With circuit breaker A8CB1 ON and neutral
safety relay A8K2 energized, +24 VDC is applied to toggle switch A8S3 which turns on the EPG which
increases ECV engine speed to 1400 - 1500 RPM. Exact engine speed is not critical as long as it is within the
1400 - 1500 RPM range. Actual engine speed is adjusted on EPG electronic controller to provide sufficient
hydraulic fluid flow to spin the NBC fan at 9000 25 RPM during NBC operation using INTERNAL power
after primary hydraulic pump adjustments have been performed.
