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Section 1. DESCRIPTION OF SETTINGS
1.1 Voltage settings
The setting voltage is determined by the positions of the six dual-in-line switches.
The sum of all the voltages shown by each respective switch position and the constant
value gives the required setting voltage. For example, an MVTU 11 with the switches
set to the position shown corresponds to a setting of 32 + 26 = 58V ac.
1 ––> 0
Voltage 2 ––> 0 Vs = (32 +∑)
setting 2 <–– 0 = 32 + 2 + 8 + 16
switches 2 ––> 0 = 58V
8 <–– 0
16 <–– 0
For other versions the setting method is identical. Refer to the nameplate on each
individual relay.
1.2 Time settings
The time setting is selected between 0.1 and 9.9 seconds by means of the
thumbwheel switches.
1.3 Trip indication
Earlier relays were fitted with hand reset mechanical flag indicators, later relays
being fitted with non-volatile hand reset LED trip indicators.
Section 2. AUXILIARY EQUIPMENT
2.1 External series resistors
The following dropper resistors pre-mounted on an external assembly, marked with
the relay serial number, are supplied with each relay when required. The part
numbers of the assemblies are listed below together with the resistor values.
The 66kΩ external resistor, Rext 2, required only on the 380/440V versions, is made
up of two 15kΩ and two 18kΩ wirewound resistors, all connected in series.
The 380/440V versions are initially calibrated with this external resistor assembly
and if the assembly or any of the resistors on it are changed, the relay must be
recalibrated.
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