Testing Static Trip III Devices
10
NOTE
When timing at values of current only slightly above pick-up,
line voltage fluctuations may cause detriggering and result in
erroneous operating times. Therefore, it is advisable to watch
the long time pick-up light to note whether trigger voltage is
maintained. In general, it is impractical to test time delay at
less than 10% above pick-up.
Short Time Delay Test
1.
Set LONG TIME CURRENT SETTING .5, LONG TIME
BAND on 30, INSTANTANEOUS PICK-UP “1 5X,”
SHORT TIME PICK-UP on 2X (0.5 Amperes) and SHORT
TIME BAND on MAXIMUM .40.
2
Press the START button and adjust the current to 1
ampere or more. In turn, press the STOP and the RESET
buttons.
3.
Close the circuit breaker, if desired.
4.
Press the START button, the delay should be .35 to .50
seconds. See Figure 5.
5.
Repeat for SHORT TIME BAND settings on the other
delay bands. Compare to Figure 5. The other phase
circuits and different values of current can be tested if
desired. Make current settings as quickly as possible to
avoid overheating.
Ground Time Delay Test
1.
Select ground with power boost, STATIC TRIP III
GROUND.
2
Set GROUND PICK-UP on 20% (010 ampere) and
GROUND TIME BAND on “Maximum,” .40.
3.
Press the START button and adjust the current to 0.5
ampere or more. (Erroneous time delay readings and
failure to trip the circuit breaker or target may occur at
lower values of current. The waveshape of current from
the test set may not provide enough power to charge the
filter capacitor in the trip device before tripping occurs.
By running the test at a higher current this effect is
minimized). In turn press the STOP and the RESET
button.
4.
Close the circuit breaker, if desired.
5.
Press the START button. The breaker should trip in 0.4
and 0.5 seconds. See Figure 5.
6.
Repeat for other GROUND TIME BAND settings and for
other pick-up and current settings, if desired. Make
current adjustments above 1 ampere quickly to avoid
oveheating.
Bench Testing Static Trip III Devices
Connections
With the static trip device away from the circuit breaker it is
necessary to make connections to the fanning strip of the trip
device via the connector supplied. A terminal block is pro-
vided on the test set to facilitate this connection. The end of
the connector strip next to the cord must connect to terminal
1, a spacer under one mounting screw of the test set
faceplate provides interference if the connections are made
incorrectly.
The terminal block is connected internally, so the phase
selector switch is used.
Test Procedure
The testing procedures are exactly the same as given in
TESTING THE STATIC TRIP ON THE CIRCUIT BREAKER
except, of course, any reference to the circuit breaker is
ignored.
Some STATIC TRIP III DEVICES may contain circuit functions
that are not completely tested by the relatively simple por-
table test set. These are described in the following sections.
Zone Selective Interlock Tests
On devices with the Zone Selective Interlock selected both
the SHORT TIME and the GROUND TIME delay bands are
affected by the incoming ZSI signal. With no incoming ZSI
signal both time bands will be on their minimum, when an
incoming ZSI signal is present both the SHORT TIME and
GROUND delay element switch to the band selected by the
front panel controls
On devices containing the ZSI function, the ZSI output circuit
provides an output signal anytime either the SHORT TIME or
GROUND pick-up values are exceeded.
Both the incoming and outgoing ZSI circuits are isolated by
an optical isolator inside the device, so some power must be
provided either externally or by making connections to the trip
devices own power supply.
Both sets of signals are brought out on the 15 pin sub “D”
connector.
Pin 1 and 2 are the device negative power.
Pin 3 is the 12 volt power.
Pin 4 is the +5 volts from the target power supply.
Pin 5 is the ZSI positive signal input.
Pin 6 is the ZSI negative signal input.
Pin 7 is the ZSI negative signal output.
Pin 8 is the ZSI positive signal output.
