PRG Bad Boy Field Service Manual - Manual (Page 107)

BAD BOY ® SPOT LUMINAIRE FIELD SERVICE MANUAL 99
AC Line Current / Power vs. Voltage
Notes:
+ Tested while running all motors except Intensity/Iris/Frost functions to allow ballast to remain stable at 1400W
output to lamp.
+ Under-Voltage Lock-Out (UVLO)
- Ballast UVLO = 165V/50Hz, 185V to recover
- 24VDC LVS UVLO = 75V/50Hz, 85V to recover
About UVLO
UVLO is an acronym for Under-Voltage Lock-Out.
On a SMPS (Switch-Mode Power Supply) the input power is regulated by a PWM (Pulse-Width Modulator). Input
power is held constant by the PWM at a value equal to the load power divided by the efficiency of the SMPS (usually
.85 to .95). The Bad Boy Electronic Ballast and the 24V DC LVS (Low-Voltage Supply) are both SMPS units.
In the table above, the input power for the Bad Boy stays constant at just over 1700 Watts throughout the usable
voltage range. As input voltage is reduced further, the input current rises to unacceptable levels for the wiring, the
circuit breaker, and the PWM transistor. There are fuses on the inputs of each SMPS that prevent fires in case of
shorts on the PCB or overvoltage at the input, but these could also be blown by a voltage sag that would cause the
input current to rise. Enter the UVLO. It is a dedicated electronic circuit added to the SMPS to monitor its input
voltage and shut down the PWM if leaving it on would cause damage.
Every high-power SMPS needs this circuit to prevent damage to the components, not just semi-conductors, but
current sensing resistors, too.
The UVLO is not adjustable, it is set by the manufacturer to what he considers a safe value for his selection of
components. We have chosen vendors that provide a conservative margin for a more reliable product. We also want
to prevent nuisance dropouts.
As voltage is decreased to UVLO level, the increasing current causes additional voltage drop in the supply lines. When
the UVLO activates, (shuts down the PWM) the voltage will rise again to its no-load value. To prevent on-off cycling
(slow oscillation) based on a sensitive threshold voltage being crossed by load/no-load conditions, hysteresis is
TEST VOLTS FREQ AMPS VA POWER PF
1 170 50Hz 10.27 1746 1735 0.998
2 180 50Hz 9.62 1732 1721 0.995
3 200 50Hz 8.56 1712 1713 0.994
4 200 60Hz 8.57 1714 1709 0.996
5 210 60Hz 8.16 1714 1707 0.997
6 220 50Hz 7.77 1709 1704 0.991
7 230 50Hz 7.47 1718 1708 0.998
8 240 50Hz 7.14 1714 1705 0.993
9 240 60Hz 7.16 1718 1702 0.996
10 250 50Hz 6.83 1708 1704 0.992
11 260 50Hz 6.62 1721 1701 0.989
12 270 50Hz 6.45 1742 1689 0.966