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
