Installation, Operation and Service Manual
LKP Series
The AD outputs indicate the present condition, having only a short time delay from an
instantaneous condition. Although the AD does not monitor every possible error condition,
it is an effective means of giving the user continual assurance of signal reliability.
A.) If the “Diagnostics Relay” is O.K. and the green LED indicators are all on: Continue
operating normally.
B.) If the “Diagnostics Relay” indicates a warning and one or more green indicators are
off:
This indicates there may be measurement errors. Consequently the metering system
should not be in full, automatic control of the rectifier. The AD relay contact output is not
intended to be the only monitor protecting the power rectifiers. Primarily, it is expected that
the customer wants to take immediate action to prevent unsafe operation. Unsafe
operation could result if the metering system is in the rectifier control loop and it
erroneously produces a significantly lower output than is true. This might cause the
rectifier control circuit to inappropriately increase the power output, perhaps to overload
levels for either the power supply or the process. So, if the metering system is in the
control loop and the “Accuracy Diagnostics” indicates a potential problem, the following
actions are recommended: FIRST- Lock out control actions that could drive the rectifier
output higher and SECOND-alert the operator.
Basically, each module inside the metering unit has four channel LEDs and 2 power supply
monitoring LEDs. The following is a description of their functionality:
A.) Line: This LED indicates whether the supply voltage to the meter unit falls within the
specified limit of +10%, -15% of nominal. Significant changes from these values will
cause this LED to turn off and trip the relay.
B.) Hall P.S.: This LED indicates whether the Hall plate supply voltage supply voltages fall
with the specified operating limits. A failed Hall plate power supply or a line voltage out
of specification will extinguish this LED and trip the relay.
C.) Channel LEDs: Each channel LED indicates the status of the corresponding channel to
aid quick troubleshooting. An extinguished channel LED can be caused by the
following:
a. A blown channel fuse;
b. a bad connection between the cable and the metering unit or cable and measuring
head;
c. a bad Hall device in the head;
d. an open /or shorted coil in the head;
e. a primary current that exceeds the dynamic measuring range of the metering unit;
f. the primary current is too low to activate all channels properly;
g. a strong external magnetic field causing a channel reversal.
Notes on items f and g above:
1.)
Under certain conditions, external magnetic fields can reverse one or more
channels in the head. The accuracy indicators will show an error in those channels
until the bus current level rises high enough to effectively turn on all channels (2-
3Vdc is the minimum reliable channel voltage). This condition can cause false
alarms. For more information on this, please refer to technical bulletin TEC9908,
“Resolving External Magnetic Field Errors”.
© 2011 DynAmp, LLC
Page 19
041837 H
