Essentials of Schneider C60H-DC DC DC Protector

Single pole (1P): usually protects the positive pole (L+). The "+" on the power side is connected to the positive input, and the "+" on the load side is connected to the positive output. The negative electrode (L -) is directly connected without passing through a protector.

Bipolar (2P): Simultaneously protect the positive and negative poles. The "+/-" on the power side correspond to positive and negative inputs, while the "+/-" on the load side correspond to outputs. Cross wiring is strictly prohibited.

Allowable power supply direction: The 250V DC version allows power supply from top or bottom, but polarity must be observed; The 500V DC version only allows power supply from the upper end (marked as' Supply from above ').

Consequences of malfunction: If the polarity is reversed, when a short circuit occurs, the arc cannot be extinguished normally, which may cause the protector to burn out or even catch fire. Therefore, it is necessary to confirm the polarity with a multimeter after wiring.

Fault analysis and on-site troubleshooting

The fault tripping of C60H-DC can be divided into two categories: overload tripping (thermal tripping) and short-circuit tripping (magnetic tripping). On site engineers should make quick judgments based on load characteristics and fault phenomena.

1. Fault types and corresponding trip characteristics

Possible causes of malfunction, characteristics of trip time, inspection steps

Immediately trip downstream short circuit after closing (<10ms), disconnect the load, measure the resistance on the load side with a multimeter, and investigate the short circuit point

After running for a period of time, trip and overload for a few seconds to a few minutes (inverse time limit), and measure whether the load current exceeds the rated value; Check for high temperature derating

Occasional tripping, irregular surge current, and unstable motor start-up to confirm load type; If it is an inductive load, it may be considered to choose a higher rated value or use a K-type trip curve (non-C type)

The fault of the handle being in the middle position after tripping has not been cleared - pull the handle to OFF and then push it to ON to reset

2. Fault Analysis of Breaking Requirements under Different Grounding Faults

According to the system grounding method, short-circuit faults may occur between different poles. The manual provides analysis of three typical faults (A, B, C):

Fault A: Monopolar short circuit to ground. At this time, the short-circuit current is U/2 (center point grounded) or U (unipolar grounded). Only the pole on the protected pole needs to have sufficient breaking ability.

Fault B: Short circuit between the two poles. The short-circuit current is U, and both poles pass through the short-circuit current. All protected poles must have a breaking ability of ≥ Isc max.

Fault C: The other polarity is short circuited to ground. Similar to fault A.

In an ungrounded system (IT system), the first single pole grounding fault only generates a small capacitive current and does not trigger a protector trip, but must be alarmed by a permanent insulation monitor (PIM) and manually cleared.

3. Common on-site problems and solutions

Problem 1: The protector trips incorrectly when the motor starts

The starting current of the motor can reach 6-8 times the rated current, and the starting point of the C-type magnetic trip is 7In, which can theoretically withstand it. If it still trips incorrectly, it may be due to excessive start-up time (thermal accumulation) or frequent motor start-up. Solution: Increase the rated current appropriately (considering derating), or replace with a higher rated protector.

Problem 2: Multiple protectors share the same power supply, and when one circuit is short circuited, the other circuits also trip

It may be due to excessive internal resistance of the power supply or voltage drop in the circuit that causes a brief voltage drop, triggering undervoltage tripping of other protectors (if any). C60H-DC itself does not have undervoltage tripping, but if undervoltage coil accessories (MN) are installed, the accessory settings need to be checked.

Problem 3: Frequent overload tripping in high temperature environment

The rated current of C60H-DC is based on 25 ° C, and it needs to be downgraded for use at 70 ° C (see module 92515 for details). If the ambient temperature is high, a higher rated current model should be selected, or ventilation and heat dissipation should be improved.

Interpretation of the Release Curve

C60H-DC adopts a C-type trip curve, which complies with the IEC 60947-2 standard. The curve is divided into two parts:

Hot trip zone (overload protection): inverse time characteristic. When the current reaches 1.13In~1.45In, it will operate for a certain period of time (up to 1 hour). The larger the current, the shorter the action time.

Magnetic release zone (short circuit protection): instantaneous action. The operating current range is 7In~10In, with a typical value of 8.5In ± 20%. When the current reaches 7 times the rated current, it may start to operate, and when it reaches 10 times, it is guaranteed to operate.