Lakeshore Learning Materials 622 - Manual (Page 60)

Lake Shore Model 620/622/623/647 Magnet Power Supply User’s Manual
Error Messages & 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:
+ 0 . 0 0 1 V
* * R E M O T E I N H . * *
O V E R V O L T A G E P R O T E C T I O N :
F A U L T O R R I D E T E C T E D .
O V P I S E N A B L E D A N D
O U T P U T S A R E D E S A B L E D
L O A D M U S T B E D I S C H A R G E D
A N D A L L U N I T S T U R N E D
O F F T O R E S E T .
O U T P U T S : *
+1.999A
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:
+ 0 . 0 0 1 V
**OVER VOLTAGE**
O V E R V O L T A G E P R O T E C T I O N :
T H E O U T P U T C U R R E N T S E T -
T I N G I S F O R C E D T O Z E R O .
O V P I S A C T I V E U N T I L 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 S : *
+1.999A
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.
Level Alarm Reached
A unique level probe zero reference feature allows
the user to define the current liquid level reading
as the “zero reference” and reads levels above or
below that reference. If turned ON, the software
level alarm notifies the user if the continuously
variable liquid level reaches the set point. The
MPS closes the FLT contacts to indicate the fault,
sounds the alarm about once per second, and
displays:
L I Q U I D H E L I U M L E V E L :
¤ R E A D I N G
U N I T S
N E X T R D G
P E R I O D
A L A R M
Z E R O R E F
C A L I B R A T E P R O B E
O U T P U T S : *
+1.999A : < O F F >
: i n ( E )
: 0 0 : 1 6
: 0 1 : 0 0
: + 1 4 . 5 < O N >
: + 0 . 0 < O F F >
¥
¥
¥
¥
¥
L V L : + 1 4 . 4 i n
F L D : + 6 3 . 4 8 k G
+ 0 . 0 0 1 V
* * L E V E L A L A R M * *
The alarm sounds until the level alarm is turned OFF.
When it is turned OFF (or disabled), the MPS opens
the FLT contacts and silences the alarm.
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:
+ 0 . 0 0 1 V
* * L O W A C L I N E * *
O U T P U T S : *
+1.999A
T H E U N I T W I L L B E T U R N E D
O F F T O A V O I D D A M A G E .
V E R I F Y A C I N P U T S E T T I N G
LO AC INPUT
LINE FAULT:
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.