Toshiba GRL150-100 Series Instruction Manual page 139

6.5.1.3 Thermal overload element THM-A and THM-T
The testing circuit is same as the circuit shown in Figure 6.5.1.6.
The output signal of testing element is assigned to the monitoring jack A.
The output signal numbers of the elements are as follows:
To test easily the thermal overload element, the scheme switch [THMRST] in the "Switch" screen
on the "Test" menu is used.
• Set the scheme switch [THMRST] to "ON".
• Enter the signal number to observe the operation at the monitoring jack A as shown in
Section 6.5.1.
• Apply a test current and measure the operating time. The magnitude of the test current
should be between 1.2 × I s to 10 × I s , where I s is the current setting.
CAUTION
After the setting of a test current, apply the test current after checking that the THM% has
become 0 on the "Metering" screen.
• Calculate the theoretical operating time using the characteristic equations shown in Section
2.7. Check that the measured operating time is within 5%.
6.5.1.5 Broken conductor detection element BCD
The testing circuit is shown in Figure 6.5.7.
I a
A
Three-phase
I b
A
Current
source
I c
A
+
DC
power
−
supply
+
DC
voltmeter
0V
The output signal of testing element is assigned to the monitoring jack A.
The output signal numbers of the elements are as follows:
Element Signal No.
THM-A 189
188
THM-T
Figure 6.5.7 Testing BCD element
⎯ ⎯
138
6 F 2 S 0 8 2 8
GRL150
TB1
-1
-2
-3
-4
-5
-6
A
Monitoring
jack
0V
TB2
-A9
-B9
E