Lakeshore Learning Materials 647 - Manual (Page 52)

Lake Shore Model 647 Magnet Power Supply User’s Manual
Troubleshooting 5-2
No delay is allowed (CAL AND ID switch 7 OFF,
down) and multiple MPS operation (CAL AND ID
switch 4 ON, up) must be selected. After the load
discharges, turn OFF all units to reset. The MPS
displays the OVP error message.
Overvoltage Protection (OVP) Circuit Activated
If the voltage across the MPS output terminals
rises above ±40 volts, the output over voltage
protection (OVP) circuit activates. The MPS also
may activate the OVP circuit in response to faults.
Upon activation, the OVP circuit uses thyristors to
crowbar the output voltage to between 1 and 1.3
volts until magnet current reaches zero. If this
occurs, change the output current setting to zero.
If the MPS detects OVP activity on power up
(output current greater than ±1 A), it turns ON the
front panel Fault annunciator, closes FLT
contacts, and sounds the alarm twice per second.
When the MPS detects the fault, it closes the FLT
contacts to indicate a fault, sounds the alarm once
per second, and displays:
O V E R V O L T A G E P R O T E C T IO N :
T H E O U T P U T S E T T IN G S A R E
F O R C E D T O 0 A A N D 1 V .
O V P IS A C T IV E U N T IL T H E
O U T P U T C U R R E N T F A L L S
B E L O W 1 A .
O U T P U T :
*
- 0 .0 0 A
+ 1 .0 0 V
O V P L O C
When output current falls below 1 A, the MPS
turns OFF the front panel Fault annunciator and
alarm, and opens the FLT contacts. When the
MPS detects no OVP activity, the Normal Display
appears.
The MPS continues to display OVP and sounds
the alarm until the user enters new output settings,
then turns them OFF. This latching action informs
the user of OVP activity. The MPS opens the FLT
contacts upon detecting OVP inactivity.
Low AC (LO AC) Detected
If the AC line falls below 80% of the nominal line
selected, the MPS enters AC Loss Mode. If this
occurs on power up, the MPS turns off the front
panel circuit breaker and displays:
T H E U N IT W IL L B E T U R N E D
O F F T O A V O ID D A M A G E .
V E R IF Y A C IN P U T S E T T IN G .
O U T P U T :
*
- 0 .0 0 A
+ 1 .0 0 V
L O A C L O C
L O A C IN P U T
L IN E F A U L T :
This indicates that the AC source does not match
the line voltage listed on the rear panel.
Upon utility loss during normal operation of a
single MPS with a charged load, the MPS disables
utility input circuitry and uses the load as an
energy source. It turns OFF the front panel Power
annunciator and turns ON the front panel Fault
annunciator. It closes the FLT contacts to indicate
a fault and sounds the alarm about once per second.
The MPS sets output voltage compliance to the level
required to maintain operation and continuously
monitors output current. If the utility recovers, the MPS
enters Remote Inhibit Mode and forces output settings
to 0 amps and 1 volt. If the utility does not recover, the
MPS activates the output OVP circuit and turns OFF
the front panel circuit breaker when the output current
drops below 10 amps. Upon power down, the MPS
enters AC Loss Mode.
NOTE: A utility loss while the MPS returns energy
from a charged load to the utility presents no hazard to
personnel working on the utility circuit. The MPS is not
a UPS. It uses the utility voltage wave form to draw
energy from the utility with a sinusoidal current and
return energy to the utility with a sinusoidal current. If
there is no utility reference signal, the MPS disables
utility input circuitry and uses the load for energy.
If utility loss occurs during normal operation in a
multiple MPS configuration, the MPS detecting the
utility loss initiates Multiple MPS Remote Inhibit Mode
by closing the FLT contacts and turning off the front
panel circuit breaker. Then the remaining MPS units
enter Multiple MPS Remote Inhibit Mode.
High AC (HI AC) Detected
Any time the AC line rises above 120% of the nominal
line selected, the MPS turns off the front panel circuit
breaker and enters AC Loss Mode. This halts
excessive utility voltages to internal circuitry. If this
occurs on power up, the MPS turns off the front panel
circuit breaker and displays:
- 0 .0 0 A
+ 1 .0 0 V
H IA C L O C
T H E U N IT W IL L B E T U R N E D
O F F T O A V O ID D A M A G E .
V E R IF Y A C IN P U T S E T T IN G .
O U T P U T :
*
H I A C IN P U T
L IN E F A U L T :
Overtemperature Detected
If the MPS detects internal over temperature or other
internal fault, it activates the OVP circuit, turns off the
front panel circuit breaker, and then turns itself off.
OVP stays active until it completely discharges the
load. If the heat sink temperature exceeds 95 °C (203
°F), the MPS displays:
- 0 .0 0 A
+ 1 .0 0 V
T E M P L O C
T H E U N IT W IL L B E T U R N E D
O F F T O A V O ID D A M A G E .
IN T E R N A L T E M P T O O H I.
O U T P U T :
*
IN T E R N A L
T E M P F A U L T :