Frequently asked questions answered by our experts.

Closed Current= Okay-state blocked (wire break leads to tripping)
Working Current= Okay-state dropped (wire break remains undetected)

If the connected current transformers are grounded at higher measuring voltages, the device measures only about half the power. This is due to the design of the measuring inputs.
As a remedy, intermediate transformers with suitable accuracy and power are connected before the measuring inputs of the EFR4001IP, 5/5 A or 5/1 A (e.g. MBS WSK 30, part numbers 30013 or 30211).

EFR4001IP with firmware version 12720-1410-03 may experience the following problem:
- If program 9 or 10 is selected and
- the device is disconnected from the supply voltage for longer than 7 days,
- then a reset loop (device briefly switches on and then off again) may occur after the supply voltage is reconnected.

- Press the joystick button of the EFR4001IP upwards for >2sec,
- This takes you to the reset menu, which is displayed for 2min.
- During this time the device can be reached via the website.
- On the web page, a program <9 must be selected under Configuration.
- After that, the device is accessible again and starts as usual.

A firmware update (version 12720-1410-04) is available for download.

Closed Current= Okay-state blocked (wire break leads to tripping)
Working Current= Okay-state dropped (wire break remains undetected)

For 3-phase voltage relays without neutral connection, the voltage is evaluated to an artificial neutral point. The scale is calibrated for single-phase voltage change. With single-phase voltage change, the neutral point shifts in the direction of the phases with the higher voltage. Symmetrical voltage change results in larger voltage changes compared to the (unchanged) neutral point. As a result, the device switches earlier.

Electronic-current transformers have an inner diameter of 11 mm. Insulated switching wires and stranded wires up to approx. 35 ø nominal cross-section and UL-approved stranded wires up to AWG 4 can be inserted through.

Electronic-current transformers are practical switches. The possible length of the connection cable solely depends on the external circuit.

In devices with software version up to and including 0-07: Strong electromagnetic interference caused by lightning, or switching operations in the control cabinet could cause the device not to switch itself back on again. Remedy is possible by measuring against N and switching to program 1. Alternatively, the device can be sent to the factory for a firmware update.

For UFR 1000 delivered until April 2009 (up to software version 0-05), the devices switch off the two output relays immediately when the menu item "Simulation" is selected. From software version 0-06 (press the "Set" key for 10 seconds to display the software version), values can be simulated for voltage and frequency to test the settings. For details, please refer to the operating manual.

If feedback contact monitoring is activated ("trEL" not equal to "oFF"), the UFR1001E also detects failed switch-on attempts. (feedback signal missing)
If the UFR1001E should not make any further closing attempts (e.g. circuit-breaker with thermal or overcurrent monitoring), this can be prevented by a jumper between terminal E1 / E2 and the setting "vSr" = "Y1Y2". As a result, the closing operations are no longer monitored,
Switch-offs, on the other hand, are.

The fallback ratio is the quotient between the value at which an overshoot is detected and dAL starts and the value at which dAL stops running if it falls below again before dAL expires.

The component certificate explicitly confirms the fallback ratios <2%. (1.02 for undervoltage/underfrequency; 0.98 for overvoltage/overfrequency).

Nevertheless, the drop-out ratios can be checked as follows:
- Set dAL to a longer time (e.g. 5.00s).
- exceed/fall below limit (e.g. at U< = 0.8 * Un to 0.78 * Un)
- back again just into the good range (in the example to 0.81 * Un)
- wait min. 5.00s (>= set dAL)
If no triggering takes place, the drop-out ratio is <2%.

Although VDE-AR-N 4110:2018-11 does not require single-fault safety, the UFR1001E is single-fault safe due to its 2-channel design. (as required by VDE-AR-N 4105:2018-11).
Both channels constantly monitor each other. In the event of a detected fault (even internal), both output relays drop out and do not switch back on automatically.
Should one of the two output relays stick, the other output relay still disconnects. (Series connection)
Thus, the output signal of the series-connected NOC can be used as a life contact.
Since VDE-AR-N 4110:2018-11 does not require single-fault safety, K1 can also be used to disconnect the tie switch and K2 as a life contact.
Certificates and technical information

The entire settings and the simulation mode can be locked.
If the LED lights up, the UFR1001E is locked.
If an attempt is made to change a setting in the locked state, "LoC" is displayed for 3s.
Setting procedure Sealing/locking ON (OFF):
- Remove seal if present (authorized person only)
- Switch on the control voltage on the UFR1001E.
- Slightly lift the pushbutton cover and rotate it by 180
- Press the button very hard on the button cover (LED starts flashing)
keep pressed until - LED lights up green
For sealing, a "standard" seal can be used, e.g. for electricity meters.

The drop-out ratio is the ratio between the drop-out value and the pickup value. Here, the excitation value is the value at which reaching the limit value is detected and the response delay time dAL starts.
The release value is the value at which "dAL"(alarm delay) stops running if it is reached before "dAL" has elapsed.
For easy measurement of the fallback ratio, activate the "ruEF" function.
Function while "ruEF" is active: When limit value is reached (="dAL" starts) → relay OFF. When the
fallback value is reached (= "dAL" aborted) → relay ON.
Drop-out ratios can only be checked for U>>, U>, U<, U<< (f, zero-sequence voltage and 10min mean value
not). To test e.g. U>>, U> must be switched "off".
Under the menu item "rEL" →"doFA" "ruEF" can be selected. The "Time" LED flashes when "rvEF" is active.
To switch off the function, call up "rEL" → "doFA" → All and confirm with "Set". Here, the switch-back delay time "doF" for all alarms can be set together to the values required by the network operator. After 600 s, the function switches off automatically.

Operating manual

Is a test terminal strip required for the UFR1001E and how must it be designed?

A test disconnect terminal strip or test disconnect terminals have been mandatory for protective devices according to VDE-AR-N 4110:2018-11 and BDEW since 2008. (See e.g. VDE 4110 -> Interfaces for protective function tests).

To carry out a protection test, we recommend routing the following connections on the UFR1001E via a test disconnect terminal:
A1 + A2 (control voltage Us)
11 + 12 +14 (relay K1); 21 + 22 +24 (relay K2)
Y0 + Y1 + Y2 (feedback contacts, or better use a separate signal contact)

The following terminals, for example, are suitable:
- Phoenix Contact URTK6 with safety test socket 4mm (on both sides!) and disconnect slider.
- Wago TOPJOB® S 2-wire disconnect and measuring terminal block with touch-proof test sockets; test plug Ø 4 mm

The UFR1001E has a passive island grid detection (voltage and frequency).
A single-phase or multi-phase interruption of the EZE supply line is not suitable for checking the island grid detection using a passive method.

To measure 2-phases to neutral, connect one phase to input L1, the second phase to inputs L2+L3 and neutral to input N. The UFR1001E will then measure the voltage between the two phases and neutral (N) and will switch off if the voltage in one of the phases reaches a limit value.

(N) connected – only for programs with N
It will not measure the voltage between the phases. It measures phases to “0” (N)!
One phase Application connect L1-L2-L3, 2 phase Application L1/L2+L3 (only Pr. 5, 7,10,13 and 20)

Link 1

How does the UFR1001E comply with the reverse switching ratios according to VDE-AR-N 4110:2018-11?
The certificate confirms on page 7
compliance with the drop-out ratios. These are permanently stored in the device software and cannot be changed.
The drop-out ratio has nothing to do with the adjustable hysteresis.


Please see sample connection plan
Sample connection plan

Closed Current= Okay-state blocked (wire break leads to tripping)
Working Current= Okay-state dropped (wire break remains undetected)

Suction does not switch on although machine is running for at least one minute.
The current consumption of the machine is too low or the response threshold is too high.

Reduce response threshold by potentiometer or via parameter (STW with display).
For STW devices without setting option, loop cables several times through the STWA1(H) current transformer.

50m is usually no problem. Significantly longer connection cables are possible. Shielding may be required when laying parallel to power lines.

Machine current in off state is higher than the response threshold / reset threshold.

The response threshold of the current relays must be increased so that a small current is suppressed and a current flow is only detected when the main motor is switched on.

For STW devices with potentiometer or display, set the response threshold correspondingly higher.
For STW devices without setting option, a resistor (0.25 W / 200 V) must be connected in parallel with the STWA1(H) current transformer before the relevant input of the current relay.
For changing the response threshold by the factor x, we recommend the following resistor values: 2x/750 Ohm, 4x/330 Ohm, 10x/120 Ohm. Because of the large tolerances to be taken into account, we recommend that the best values be determined by trials.

The STWA1S electronic current transformer is not designed for connection to STW relays. It has a residual current of 0.6 mA, which means that the input on the STW would always detect a running machine.
Alternatively, the STWA1SEH current transformer can be used.
Alternative STWA1SEH

Closed Current= Okay-state blocked (wire break leads to tripping)
Working Current= Okay-state dropped (wire break remains undetected)

PTC thermistor sensors are often provided with notes that the measuring voltage must not exceed 2.5 V. Measuring inputs of PTC thermistor tripping devices, however, usually have significantly higher voltages in no-load operation (up to 20 V). This is not critical, since the voltage collapses immediately when a sensor is loaded. With cold (low-impedance) sensors, the measuring voltage must not exceed 2.5 V. For hot (high-impedance) sensors, it must not exceed 7.5 V.

How can I set at which temperature the relay switches off?
PTC relays have a fixed response point at approx. 3 to 4 kΩ. The actual switching point depends on the PTC sensor, which becomes highly resistive at a certain nominal response temperature (NAT). As a rule, up to 6 PTC thermistors can be connected in series. PTC thermistors with different NATs may even be connected in series (e.g. for monitoring winding and core, or bearing temperatures to different values.

For temperature relays for Pt 100 with adjustable hysteresis, e.g. ZIEHL -temperature relay type TR, PTC thermistors can also be connected to the sensor inputs. For this purpose, the input is programmed for the connection of a 2-wire sensor and a resistor 150 Ohm is connected in parallel to the PTC thermistor circuit. When the switching point is set to 115 °C and hysteresis 20 °C, the device switches like a PTC-resistor relay. Temperature displays and analog outputs are unusable. We recommend the use of PTC thermistor relays type MS ... .

We do not have any numerical values for the failure rate from the manufacturer of the PTC thermistor pills. As an empirical value from the ZIEHL company, a failure rate of ≤ 10 fit can be assumed. This corresponds to comparable values for components made of ceramic material (e.g. ceramic capacitors). From this, an MTBF of ≥ 100 years can be calculated. These figures depend on the failure criteria, the stress and the operating time. A supplementary specification for estimating the service life for PTC thermistors of type MINIKA® under operating conditions can be made for PTC thermistors of similar design (e.g. for level monitoring). Here, the manufacturer has provided information on > 5000 switching cycles.

This is usually not possible in the installed state. The cold resistance of a 3 PTC thermistor chain is approx. 60 to max. 750 ohms (typically 150-300 ohms): This means that, at best, PTC thermistors from a production batch can be used to draw a conclusion about short-circuiting of a sensor in the chain. Up to 20 K before reaching the nominal response temperature, the resistance can even drop as the temperature rises. The trigger point at overtemperature can only be determined by practical tests (heating in an oil bath). The nominal response temperature can be recognized by the colors of the connecting wires (see ZIEHL catalog). ATTENTION: Measuring voltage max. 2.5 V.

Since PTC thermistors already have a very high resistance and the resistance changes from <250 Ω to over 4 kΩ in the range of the nominal response temperature, the ohmic resistance plays a very minor role, so that lengths of 500 m or longer are generally not critical. The measuring circuit wires are to be laid as separate control wires. The use of cores from the motor supply line or other main power lines is not permitted. If strong inductive or capacitive interference is to be expected from parallel power lines, shielded control lines must be laid.

Sensor lines can be extended with a screened cable, e.g. LIYCY 3*0.34mm²

See link
Information and instructions

The use of MAC-based filtering on the DHCP server can be useful for security reasons.
ZIEHL IP devices can be enabled by the following entry in the MAC list:
This is an entry with the ZIEHL manufacturer ID and a WildCard.

The MSF 220 V (VU) has short-circuit and open-circuit monitoring in the sensor circuit. Any fault in the sensor circuit results in a prewarning. In this case, the "Sensor" LED lights up and the LED of the faulty sensor circuit flashes. To test the PTC thermistor input, a potentiometer (e.g. 0-10 kΩ) can be connected to the input to be tested. In doing so, the resistance must not be increased too quickly (leads to evaluation as an interruption). It is easier to test only the 3 points short circuit (bridge in sensor input), normal operation (PTC thermistor connected) and interruption (terminals disconnected). If these are evaluated and displayed correctly, it can be assumed that the sensor inputs are evaluated correctly. The outputs are tested by pressing the test button for a long time. In the case of devices delivered from approx. the beginning of 2004, which can be recognized by the width of the housing (only 70 mm), the short-circuit and open-circuit monitoring can be switched off for 10 minutes by pressing the button even longer (until the "ON" LED changes its flashing frequency).

A trigger occurs immediately or a few seconds after switching on?
The RESET/TEST key has been pressed too hard or with an unsuitable tool and is jammed, thus a test cycle runs immediately after switching on. Remedy: "Unjam" the button. (The key has been changed in the meantime).

The inputs can be connected in parallel to use a common reset button. The function has been tested with up to 4 devices. However, in order to be able to exclude malfunctions (e.g. due to contact resistances or contact problems), we recommend using a potential-free contact for each input.

Address for obtaining suitable seals for STR100, e.g. type Pullfly:
CHEMTEC Sicherungssysteme
Lindenweg 2, 60552 Röthenbach, Germany
Phone: +49-9120-18 34 22
Fax: +49-9120-18 34 24

In case of regular and non plausible alarms, check the setting of the cyclic test.
To prevent seizing bearings of e.g. fans or pumps, a cyclic test can be activated for each alarm. Depending on the selected program, this is also preset at the factory.
If an alarm with an activated cyclic test is used e.g. for transformer shutdown, you will regularly get an unwanted transformer shutdown.