Carrying Out The Cable Check - Siemens SIMATIC ET 200SP Manual

5.4.7

Carrying out the Cable Check

The isolation of the cable is checked. The cable isolation is faulty if a maximum DC leakage
current is exceeded when the maximum voltage of the frequency converter is applied.
In this phase the breakers of the vehicle are open. This was ensured through checking for
external voltage (see chapter Checking whether the voltage is de-energized on the charging
cable (Page 44)).
Parallel to the cable check described below, the error output of a mounted insulation monitor
is checked. This can be created at the hwError input.
● Bit 0: Insulation warning
● Bit 1: Insulation fault
.
The cable check is carried out in the following steps in the DIN70121 function block:
1. Closing of the breakers
If the PreCharge breaker is activated, it is now closed. The DC breaker remains open.
However, if the precharge breaker is deactivated, the DC breaker is closed instead. If the
DC breaker of the function block is deactivated as well, the check nevertheless continues
to the next step. (the check now assumes that the DC breaker is activated from the
outside).
2. Determining the target voltage to be set at the frequency converter
Calculation of the target voltage:
Min(in.evseCfg.maxVoltageInVolt, out.ev.limits.maxVoltageInVolt)
3. Setting the frequency converter to target voltage
The frequency converter is switched to voltage control (enableCurrentControl:=false) and
the target voltage to be set is passed to the frequency converter. The specified target
current is parameterized at the DIN_70121 function block and is transferred to the
frequency converter. Time monitoring takes place in the function block whether the actual
value of the voltage has followed the setpoint of the voltage within the time parameterized
in "in.evseCfg.maxTimeRampUpDown".
The maximum voltage is reached when U ≥ (Target voltage - in.evseCfg.emvInVolt)
4. Perform current measurement for 10 seconds
After the frequency converter has reached the specified maximum voltage, a 10 second
measurement phase begins in which the measured current is checked by the DIN_70121
function block. In the process a constant check is carried out whether the maximum
permitted DC leakage current has been exceeded. If the shunt is activated, its current
flow is deducted from the measurement.
5. Shutting down the frequency converter
After the 10 seconds have expired, the frequency converter is reduced to the minimal
voltage. The current specification for the frequency converter is 1 ampere if the target
current is greater than 1 ampere. Otherwise the specified target current is used for the
current specification.
The minimum current is reached when
U ≤ (in.evseCfg.minVoltageInVolt + in.evseCfg.emvInVolt)
Technology module TM ECC PL ST (6FE1242-6TM20-0BB1)
Manual, 07/2019, A5E43919893B-AA
5.4 Principle of operation of the DIN_70121 function block
Programming
45